PVS 50 P 33(LP) HA Old 02 143

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Table of Contents
News
- Business
- Editorial
Technology
Features
Products
Regulars
- People/Sudoku

SILICON PHOTONICS

Intel and UCSB

team comes up

with hybrid laser

Switchable lotus

effect creates self-

cleaning surfaces

SURFACE TREATMENT

IN-SITU METHOD

ENSURES PRECISE

OPTICAL LAYERS

OPTICAL MONITORING

BEAM SHAPING

DOEs offer big

benefits thanks to

unique properties

October 2006 Issue 143 The European magazine for photonics professionals optics.org

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NEWS

5Business Intel and UCSB scientists claim hybrid silicon laser

revolution •Consortium wins funding to tackle LCD recycling

•Photonex focuses on interaction

9Editorial New technology galore

TECHNOLOGY

11 Applications Embedded LEDs light up clothing •Sommelier

robot helps choose wine •Laser-etched silicon delivers a response

in the near-infrared

16 R&D Doubled VECSEL emits light in the ultraviolet

•‘See-through’ silver boosts LEDs

17 Patents UK imaging firm AST receives US patent for its

infrared camera •Kodak signs up Tohoku of Japan as licensee of

OLED technology

FEATURES

19 Eye scan shows first sign of Alzheimer’s disease

Scanning the lens of a human eye with infrared laser light can

reveal the earliest signs of Alzheimer’s disease in a matter of

seconds, according to US start-up Neuroptix.

23 Lasers meet fluids: an integrated approach

An optical manipulation and analysis platform that can fit onto

a fingernail could significantly change the field of microfluidics.

26 ZnO-based LEDs begin to show full-colour

potential

Start-up MOXtronics has recently produced the first coloured

ZnO-based LEDs. Although the efficiency of these LEDs is not

high, the emitters have the potential to outperform GaN rivals.

29 In situ method drives up yields and reduces costs

There is a lot more to making an optical filter than meets the eye.

Dominik Goessi looks at the role of in situ monitoring in the

production process and reviews the technology.

33 Hybrid diffractive optics offer an elegant solution

Thanks to a set of unique properties, diffractive optical elements

have the potential to transform light into almost any desired

distribution. Joshika Akhil gives the low-down on the technology.

PRODUCTS

37 Oscilloscope•Chromatic confocal sensors •Colour CCD camera

REGULARS

50 People/Sudoku

EDITORIAL

Editor Jacqueline Hewett

Tel: +44 (0)117 930 1194

jacqueline.hewett@iop.org

News editor James Tyrrell

Tel: +44 (0)117 930 1256

james.tyrrell@iop.org

Science/technology reporter Darius Nikbin

Tel: +44 (0)117 930 1247

darius.nikbin@iop.org

Production editor Alison Gardiner

Technical illustrator Alison Tovey

EUROPE/ROW SALES

Group advertisement manager Adrian Chance

Tel: +44 (0)117 930 1193

adrian.chance@iop.org

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Tel: +44 (0)117 930 1260

robert.fisher@iop.org

Deputy advertisement manager Cadi Jones

Tel: +44 (0) 117 930 1090

cadi.jones@iop.org

Senior sales executive Katrina Davis

Tel: +44 (0) 117 930 1284

katrina.davis@iop.org

US SALES

US sales executive Meghan Cavanaugh

IOP Publishing Inc, Suite 929, 150 South

Independence Mall West, Philadelphia PA 19106, USA

Tel: +1 215 627 0880. Fax: +1 215 627 0879

cavanaugh@ioppubusa.com

CHINA SALES

Ann Hou

Shenzhen Yongge Advertising Co Ltd, Rm 1106,

Xinwen Building, No. 2 Shennan Zhong Road,

Shenzhen, Guangdong, PRC

Tel: +86 755 82091822. Fax: +86 755 82090566

ann@indus-sources.com

ADVERTISING PRODUCTION

Advertising production coordinator Rachel Sermon

Tel: +44 (0)117 930 1277

rachel.sermon@iop.org

Advertising production editors Jo Derrick/Mark Trimnell

CIRCULATION AND MARKETING

Subscription and circulation manager Jenny Brown

Tel: +44 (0)117 930 1034

jenny.brown@iop.org

ART DIRECTOR

Andrew Giaquinto

PUBLISHER

Geraldine Pounsford

Tel: +44 (0)117 930 1022

geraldine.pounsford@iop.org

OPTICS & LASER EUROPE

Dirac House, Temple Back, Bristol BS1 6BE, UK

Tel: +44 (0)117 929 7481

Editorial fax: +44 (0)117 925 1942

Advertising fax: +44 (0)117 930 1178

Internet: optics.org/ole

ISSN 0966-9809 CODEN OL EEEV

SUBSCRIPTIONS

Complimentary copies are sent to qualifying

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and Mexico). CONTACT: IOPP Magazines, WDIS Ltd,

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Issue 143 October 2006 Contents

IMEC installs ASML’s EUV

Alpha Demo Tool. p5

UK researchers’ doubled

VECSEL emits UV light. p16

Chip combines microfluidics

and integrated optics. p23

ZnO-based LEDs look set to

challenge GaN devices. p26

SILICON PHOTONICS

Intel and UCSB

team comes up

with hybrid laser

Switchable lotus

effect creates self-

cleaning surfaces

SURFACE TREATMENT

IN-SITU METHOD

ENSURES PRECISE

OPTICAL LAYERS

OPTICAL MONITORING

BEAM SHAPING

DOEs offer big

benefits thanks to

unique properties

October 2006 Issue 143 The European magazine for photonics professionals optics.org

For the latest news on optics and photonics don’t forget to visit optics.org

Cover (Evatec) Optical

monitoring systems give

manufacturers a high level

of process control. p29

OLEOct06CONTENTSp03 25/9/06 15:15 Page 3

Imagine. Together.

www.ELCAN.com/create

NORTH AMERICA • PRECISION OPTICS AND ELECTRONICS • EUROPE

ELCAN was there at the invention of 35mm photography and for over 150 years

has excelled at developing new optical technologies. ELCAN works with customers

seeking to revolutionize the science of medical imaging and photonic treatments.

From initial design and testing to cost-efficient high-volume production, ELCAN

is your complete optical and electronic manufacturing partner.

Delivering advanced medical products to market quickly takes an optics and elec-

tronics manufacturing partner of uncommon experience that knows how to deliv-

er dependable “no doubt” performance. Our unrivaled capabilities in designing

and building precision systems for digital radiography, endoscopic laser surgery,

ophthalmic examination and many other health science applications makes us

your partner of choice.

You have a vision. Let us show you the light.

OLEOctAdElcan4 29/8/06 10:33 Page 1

Intel and UCSB scientists claim

hybrid silicon laser revolution

NEWS

BUSINESS 5EDITORIAL 9

OLE • October 2006 • optics.org/ole

SILICON PHOTONICS

By Michael Hatcher

A huge increase in speed for high-

end computing applications could

be on the cards after a US team

announced that it had created the

world’s first electrically pumped

“hybrid” silicon laser. In making

the device, researchers at Intel and

the University of California Santa

Barbara (UCSB) claim to have

combined the light-emitting prop-

erties of indium phosphide (InP)

with the manufacturability of sili-

con for the first time.

“This could bring low-cost, ter-

abit-level optical ‘data pipes’ inside

future computers and help make

possible a new era of high-perfor-

mance computing applications,”

said Mario Paniccia, director of

Intel’s Photonics Technology Lab.

In the hybrid structure, InP mat-

erial generates and amplifies light

to create the laser, while the silicon

structure acts as a laser cavity and

is used to route and control the

emission. Light enters into the sili-

con through a physical effect

known as evanescent coupling.

The initial laser made by Intel emits

at 1.58 µm, although this wave-

length can be adjusted by modify-

ing the silicon waveguides used.

According to Intel, the key to

making the device is the use of a

low-temperature oxygen plasma.

This creates a thin oxide layer on

the surface of both materials.

When heated and pressed together,

this oxide layer acts like a glue and

fuses the two different materials

into a single chip. Intel claims that

unlike other methods that have

been tried, this eliminates any

problems due to lattice mismatch

between the two materials.

UCSB’s Jon Bowers says that

this bonding method can be used

at the die, partial-wafer and full-

wafer level, and could become a

solution for large-scale optical

integration on a silicon platform.

Intel’s chief technical officer

Justin Rattner says that if the latest

development can be scaled up for

mass production, it ought to solve

the cost issue with current photonic

chip manufacturing. Presently, the

cost of a laser chip for communica-

tions can be up to 100 times that of

a silicon chip.

Infinera, the Sunnyvale, CA, US,

company that has developed an

integrated approach for current

telecommunications applications,

says that Intel’s work is a “great

endorsement” of the photonic

integration concept.

However, it disagrees with Intel’s

conjecture that InP is an “exotic”

material that is inherently expen-

sive. Infinera believes that the cost

of manufacturing devices is dic-

tated more by the level of volume

production required.

Intel has previously claimed sili-

con photonics breakthroughs,

such as last year’s optically excited

Raman laser. However, this latest

research is the first to detail a chip

that can be powered electrically.

The company says that its vision is

to produce chips containing hun-

dreds of hybrid silicon lasers using

established high-volume, low-cost

manufacturing methods.

Michael Hatcher is editor of

Compound Semiconductor

(www.compoundsemiconductor.net).

IMEC of Leuven, Belgium, which is

Europe’s leading independent

nanoelectronics and nanotechnol-

ogy research institute, has taken

delivery of an extreme ultraviolet

(EUV) Alpha Demo Tool, developed

by Dutch firm ASML.

EUV is the most likely candidate

technology for the 32 nm half-

pitch node. Over the past two

years, IMEC and its partners have

been busy building up the photore-

sist know-how necessary for EUV

lithography, which can now be

exploited using the new tool.

“We are convinced that we will

be able to make EUV available for

production at the 32 nm half-pitch

node,” said Luc van den Hove, vice-

president of Silicon Process and

Device Technology at IMEC.

Along with more than 30 litho-

graphy programme partners,

including nine of the world’s lead-

ing IC manufacturers or foundries

– Infineon, Intel, Matsushita/

Panasonic, Micron, Philips Semi-

conductor, Samsung, STMicro-

electronics, Texas Instruments and

TSMC – IMEC leads the world’s

largest research and development

effort on lithography targeting the

(sub-)32 nm node.

IMEC installs full-field EUV system

LITHOGRAPHY

Hybrid laser: when a voltage is applied to the bonded chip, light generated from

InP-based material couples directly into a silicon waveguide. Intel hopes that the

device will drive a new era of high-performance computing applications.

ASML’s Alpha Demo Tool will be put

through its paces at IMEC.

ASML

Intel

OLEOct06NEWSp5-9 25/9/06 15:53 Page 5

Consortium wins funding

to tackle LCD recycling

NEWS

BUSINESS

DISPLAYS

6OLE • October 2006 • optics.org/ole

Scientists from the University of

York, UK, have won a competition,

organized by the UK government’s

Department of Trade and Industry

(DTI), to investigate ways of extract-

ing and recycling liquid crystals

from waste LCD devices.

Researchers estimate that the

value of recycled LCD material from

the UK alone could be as much as

$60 m (747.3 m) per year.

Some 40 million LCD television

sets were sold worldwide in 2005

with expected sales likely to exceed

100 million by 2009. However, the

chemicals they contain are poten-

tially hazardous, and technologi-

cal advances are so rapid that

society is already discarding mil-

lions of LCD screens each year.

The York team is part of a con-

sortium of nine partners and is

supported by both the Resource

Efficiency and the Displays and

Lighting Knowledge Transfer Net-

works. The DTI is funding 50% of

the total project development bid

worth £1.7 m (72.5 m).

LCD screens usually comprise

two glass sheets, with a thin film of

viscous liquid-crystal material

deposited between them. The mat-

erial is made up of a combination

of up to 20 different compounds,

typically polar organic compounds

that are often fluorinated. EU legis-

lation now prevents disposal of

electronic materials in landfill.

Incineration, the other disposal

route, has also been banned.

“We have developed a technology

that offers a clean, efficient way to

recover the mixture of liquid crys-

tals from waste LCDs,” said Avtar

Matharu, of York’s Department of

Chemistry. “Once recovered, the

liquid-crystal mixture will be recy-

cled into LCDs or separated into indi-

vidual components for resale.”

So-called active disassembly, is

an important feature of the project.

To aid recycling, liquid-crystal mat-

erial stuck between the glass layers

needs to be isolated easily. For

example, this could be achieved by

inserting intelligent polymers in

between display panels to pop them

apart for dismantling.

LASERS

nLight, US, a manufacturer of high-

power semiconductor lasers, has

acquired the assets of Flextronics

Photonics, a US subsidiary of

Singapore-based Flextronics

International. The acquisition adds

an array of new fibre-coupled and

hybrid microelectronics to nLight’s

existing range of products.

IMAGING

Infrared-camera developer Cedip

Infrared Systems, France, has

reported that its turnover for the

first half of 2006 totalled 77.7 m,

representing growth of 19% on the

same period last year. Exports

accounted for 86% of sales, with

strong growth in Asia–Pacific. The

firm has also announced the

signing of a new million-dollar

contract with the US Army.

LASERS

Sony has blamed delays in the

production of GaN-based laser

diodes as it put back the European

launch of its PLAYSTATION 3

console from autumn 2006 to

March 2007.

SPECTROSCOPY

PerkinElmer, a developer of

photonics and health science testing

systems, has acquired Avalon

Instruments, Belfast, UK. The

acquisition will add a range of bench-

top dispersive Raman spectrometers

to PerkinElmer’s portfolio.

For more business news from the

world of lasers, optics and

photonics, please visit

optics.org/optics/Business.do.

IN BRIEF

Fibre laser specialist IPG Photonics

is looking to float on the US stock

market to raise cash that will be

partly used to fund its diode manu-

facturing expansion. The firm has

filed a registration statement with

the US government’s Securities

and Exchange Commission (SEC)

for a proposed initial public offer-

ing (IPO) of its common stock.

Although the firm is yet to reveal

details of the anticipated timing

and value of the IPO, its S-1 regis-

tration statement with the SEC does

contain plenty of information.

IPG’s high-power, diodes are key

components in the company’s

fibre laser systems, which are used

in materials processing applica-

tions, and provide a much smaller,

more convenient alternative to tra-

ditional carbon dioxide and solid-

state lasers.

Currently with 900 employees

and 300 customers, IPG posted

sales of $64.9 m (750.6 m)and a

net profit of $6.1 m in the first half

of 2006. Its chief executive officer

and founder Valentin Gapontsev is

the majority shareholder, owning

62.6% of shares prior to the IPO.

Valentin’s son Denis Gapontsev

acts as vice-president of research

and development at the firm.

On its balance sheet, IPG lists

total assets worth $132 m, with

cash and cash equivalents

totalling $11.3 m and long-term

debt of $22.7 m.

IPG Photonics files

for public offering

FIBRE LASERS

LCD recycling know-how: (left to right)

Avtar Matharu and his colleague John

Goodby from the University of York’s

Department of Chemistry, UK.

University of York

OLEOct06NEWSp5-9 25/9/06 15:54 Page 6

Photonex focuses on interaction

NEWS

BUSINESS

EXHIBITIONS

OLE • October 2006 • optics.org/ole

OPTICAL FILTERS

UV Filters, NBP

LWP, SWP, BP, Custom

Fluorescence

Colour Imaging

Raman Spectroscopy

Microscopy

www.lasercomponents.co.uk

The 15th annual Photonex exhibi-

tion returns to Stoneleigh Park

near Coventry in the UK on 18–19

October. With 125 exhibitors and

more than 1500 visitors expected,

a dedicated demonstration area

and packed programme of sup-

porting seminars, the event will

certainly offer something for every-

one with an interest in photonics.

“This year’s Photonex will be an

interactive and educational oppor-

tunity,” organizer Laurence Dev-

ereux told OLE. “It is only face to

face that you can truly have a

dynamic discussion, and by seeing

live demonstrations you can make

a real evaluation of the technol-

ogies available to you. We have

arranged to bring more technol-

ogies than ever to this year’s event.”

One of the new additions this

year is the “Wonder of Photonics”

demonstration area, which is being

managed by Photonics Cluster, UK.

According to Devereux, visitors

will be able to see how users in

areas such as healthcare, automo-

tive and aerospace are applying

photonics technologies.

“There will be 10 demonstrations

running throughout both days in a

separate area on the exhibition

floor,” said Devereux. “Photonics

Cluster has invited people to demon-

strate in areas such as laser scan-

ning, optical sensing, thermal

imaging and personal projection.

All attendees can visit this area free

of charge.” Companies demonstra-

ting their technologies include TRW

Conekt, Light Blue Optics, Faro,

Rofin Baasel and FLIR Systems.

In addition, visitors can expect to

see a range of demonstrations at

exhibitors’ booths. For example,

Pro-Lite Technology will be showing

off the ProMetric imaging sphere

developed by Radiant Imaging of

the US. Pro-Lite says that the prod-

uct is the only non-moving-part

goniophotometer on the market,

measuring the luminous intensity

distribution from an LED over 2 /sr

in a couple of seconds. Various spec-

troscopic techniques will also be on

show, such as fluorescence imaging

at LOT Oriel’s booth and single pho-

ton counting at Alrad’s stand.

According to Devereux, two

other opportunities that delegates

should take advantage of at Pho-

tonex are speaking to the newly

launched UK photonics knowledge

transfer network (KTN) and meet-

ing representatives of delegations

from Singapore and Switzerland.

“The KTN will have a stand at

Photonex and they are very keen

for people to come and talk and be

involved,” said Devereux. “The

Singapore delegation has expertise

in silicon photonics and wants to

build links with UK companies.”

Running alongside Photonex is a

comprehensive programme of sem-

inars, all of which are free to attend

(see box). Just one of the events on

offer is the one-day “Innovations in

Imaging” seminar, which has been

put together by SPIE Europe.

Delegates attending the seminar

will be treated to a mixture of speak-

ers working in diverse applications.

Richard Duddley from NPL, UK, for

example, will share his thoughts on

optical coherence tomography.

Nigel Allinson from the University of

Sheffield, UK, will discuss the future

imaging need in academia. Bill

Proud from the University of Cam-

bridge, UK, will present work on

high-speed photography of explo-

sives and ballistics. Finally, Grant

Hall from Wide Blue will round off

the day by offering advice on how to

commercialize imaging systems.

Wednesday only

GPhotonics in Medicine,

Healthcare and Life Sciences –

Making Light Work

Organized by Photonics Cluster,

UK, this one-day seminar will

feature a series of talks focusing

on biophotonics.

GInnovations in Imaging –

Analysis, Insights and Ideas for

Imaging Applications

This one-day event has been put

together by SPIE Europe and

looks at high-speed imaging in

industries such as medicine,

automotive and defence.

Wednesday and Thursday

GImaging for Science and

Industry

This one-day seminar, organized

by UKIVA, is free to attend,

although advance booking is

requested. Topics will range from

extracting 3D information from 2D

images to the use of infrared

images for machine vision.

Thursday only

GApplied Photonics in High-

technology Engineering

This one-day seminar is organized

by Photonics Cluster, UK.

For more information on all

aspects of Photonex, including

the series of seminars running

alongside the main event, please

see www.photonex.org.

Photonex events

Jam packed: the 2006 show features a demonstration area and a seminar programme.

OLEOct06NEWSp5-9 25/9/06 15:55 Page 7

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Project10 25/9/06 15:45 Page 1

New technology galore

NEWS

EDITORIAL

OLE • October 2006 • optics.org/ole

Welcome to the October issue of OLE. Looking

through the contents page of this issue, it is

clear that a lot has happened in the world of

optics and photonics this month. New tech-

nologies, applications and milestones all high-

light the benefits that optics can bring to society

today and in the future.

Take Intel’s announcement of the first

electrically pumped indium phosphide–

silicon laser, for example. According to the

development team, a huge increase in speed

for high-end computing applications could be

on the cards, all thanks to this hybrid laser.

Mario Paniccia, the director of Intel’s

Photonics Technology Lab, is upbeat in saying

that “this [device] could bring low-cost,

terabit-level optical ‘data pipes’ inside future

computers and help to make possible a new

era of high-performance computing

applications”. For more information, see p5.

From one success to another, details of a US

start-up pioneering an optics-based system

that probes for early signs of Alzheimer’s

disease can be found on p19. With ageing

populations, Neuroptix says that the ability to

catch this degenerative illness early and begin

treatment is enormously significant.

The Neuroptix system combines infrared

excitation, fluorescence imaging and light-

scattering analysis. It uses infrared light to

detect any build-up of “amyloid protein” in

the lens of the eye – a sign that the patient

could be at increased risk of developing

Alzheimer’s.

On p23, researchers from the University of

St Andrews in Scotland, UK, present details of

a device that monolithically integrates lasers

and microfluidic channels. “We believe that

any research group with access to

semiconductor processing facilities could

replicate the device at a cost of just a few

pounds in materials,” says the team. “We hope

that this technology can be spread rapidly

amongst the biophotonics community.”

The technology section, starting on p11,

also offers our regular round-up of

applications and R&D news. This time, we

feature fabrics with integrated LED displays,

a material that emulates the lotus effect to

produce self-cleaning surfaces and a robot

that uses infrared spectroscopy to help you to

choose a bottle of wine. I wonder how long it

will be before we see all three of these ideas

in everyday society?

Jacqueline Hewett, editor

E-mail: jacqueline.hewett@iop.org

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TECHNOLOGY

APPLICATIONS 11 R&D 16 PATENTS 17

OLE • October 2006 • optics.org/ole

DISPLAYS

Last month, Philips Research of the

Netherlands impressed visitors at

the Internationale Funkausstellung

(IFA) show in Germany by demon-

strating promotional jackets and

furniture featuring the company’s

Lumalive technology.

Lumalive textiles allow fabrics to

carry dynamic advertisements and

graphics and feature constantly

changing colour surfaces. Since

exhibiting early prototypes at IFA

2005, Philips Research has man-

aged to fully integrate Lumalive fab-

rics into garments. First-generation

jackets are now ready for commer-

cialization by companies partner-

ing with Philips Research. The

textiles are of particular interest to

those in the promotions industry

looking for a high-impact medium.

“Taking the Lumalive fabrics

from prototypes to integrated

products has been a major chal-

lenge,” said Bas Zeper, managing

director of Photonic Textiles at

Philips Research. “The light-emit-

ting textiles have to be flexible,

durable and operated by reason-

ably compact batteries. Fitting all

that into a comfortable, light-

weight garment is a considerable

engineering success.”

“Last year Philips Research dis-

played its research prototypes. This

year the jackets and furniture rep-

resent versions that are ready to go

into commercial production and

they include integrated power

sources and control electronics,”

added Zeper.

Lumalive fabrics use flexible

arrays of coloured LEDs that are

integrated into the fabric without

compromising the softness and

flexibility of the cloth. The light-

emitting textiles can then carry

dynamic messages and graphics.

According to Philips Research, fab-

rics such as curtains, cushions and

sofa coverings can even contain

the light-emitting technology.

Philips Research says that the

jackets are comfortable to wear

and that the electronics, batteries

and LED arrays are fully integrated

and invisible to the observer and

wearer. The Lumalive fabrics are

said to become obvious only when

they light up to display various

vivid coloured patterns, logos,

short text messages or even full-

colour animations.

The jackets feature panels of up

to 200 ×200 mm2, although the

active sections can be scaled up to

cover larger areas such as a sofa.

The products include features

that make them practical for daily

use. For example, when integrating

the Lumalive fabrics into a gar-

ment, Philips Research has made

the parts that cannot be easily

washed – such as the batteries and

control electronics – simple to dis-

connect and reconnect after the

garment has been cleaned. Even the

light-emitting layer can be easily

removed and refitted into the jacket.

A solar-grade (SoG) silicon derived

by metallurgical silicon purifi-

cation will increase the availability

of feedstock to the ever-hungry

photovoltaic (PV) industry, accord-

ing to its developer Dow Corning

Solar Solutions (DCSS). When the

SoG silicon is blended with tradi-

tional polysilicon feedstock, the

resulting material is said to exhibit

performance characteristics sim-

ilar to polycrystalline silicon.

The new silicon feedstock mat-

erial is called PV 1101 SoG Silicon.

Its production method from quartz

(sand) can be likened to the refin-

ing process of iron ore into steel. A

key advantage of the novel (and

confidential) process is that it

enables economical, volume pro-

duction of high-quality silicon.

PV 1101 can then be blended

with lower-grade polysilicon to

produce material of sufficient qual-

ity for photovoltaic cells. DCSS says

that this is the first commercially

available feedstock produced from

such technology using large-scale

manufacturing processes.

A major obstacle facing the

growth of solar energy in recent

years has been the availability of

silicon. To date, the solar industry

has relied on the supply of poly-

crystalline silicon, a high-grade

purity product, originally devel-

oped for the semiconductor indus-

try. However, this has meant that

the industry has in turn been sub-

ject to resource restraint.

DCSS believes that PV 1101,

produced by a different route, will

alleviate this restraint and will

offer a new source and new techni-

cal and business options for the

solar industry.

“PV 1101 is certainly one of the

most innovative technologies to

come along in the solar-energy

industry since the manufacture of

the first silicon solar cells,” said Gae-

tan Borgers, director of DCSS. “For

years now, the solar industry has

hoped to be supplied by new sources

of silicon designed and dedicated to

them. PV 1101 is a step in that

direction, which gives a means of

growth for the solar industry.”

The PV 1101 blend material has

already been tested in independent

institutes and at several of DCSS’

customer production sites world-

wide. The testing showed that the

blended feedstock exhibits perfor-

mance characteristics on a par

with polysilicon in terms of solar-

cell manufacturing and efficiency.

The typical power conversion effi-

ciency of a silicon photovoltaic cell

remains just 15–16%.

“Dow Corning has worked

closely with several customers to

test and qualify our material,” said

Rudy Miller, marketing manager of

DCSS. “The results are very posi-

tive and we have recorded a high

interest in our product. Orders

have already been placed.”

DCSS began production of

PV 1101 earlier this summer and

bulk customer shipments began in

August. The company is now pro-

gressively ramping up its PV 1101

SoG silicon production facility in

Santos Dumont, Brazil.

Purified silicon eases solar-grade supply issues

SOLAR CELLS

Lumalive jackets contain panels up to

200 ×200 mm2that can display logos

and messages. Philips Research says

that it is now ready to be commercialized.

Philips Research

Bags more: high-quality silicon in bulk.

Dow Corning Solar Solutions

OLEOct06TECHNOLOGYp11-17 25/9/06 16:18 Page 11

Sommelier robot helps choose wine

TECHNOLOGY

APPLICATIONS

SPECTROSCOPY

12 OLE • October 2006 • optics.org/ole

Choosing a bottle of wine is often a

tough task revolving around ques-

tions such as price, grape variety

and the product’s origin. Now,

thanks to a sommelier robot devel-

oped by NEC System Technologies

and Mie University in Japan, help

could be at hand to take the uncer-

tainty out of the decision.

“The robot contains a wine data-

base,” Yukie Endo of NEC System

Technologies told OLE. “The data-

base includes various attributes,

such as country, winery, colour,

taste and price. The robot automati-

cally generates questions using the

attributes of the database.”

The wine-tasting robot builds on

research by NEC and Mie Univer-

sity. The team’s first robot used

infrared spectroscopy to analyse

food and estimate the quantities of

components such as sugar and fat.

“The robot can identify the food

by referring to characteristics in the

database,” said Endo. “It uses con-

tinuous-wave infrared light and pro-

duces almost a real-time response.

Some foods are easy to distinguish;

others are difficult. Wine is a typical

example of the latter.”

Keen to take up the challenge,

Endo and his colleagues modified

their food-tasting robot to create a

sommelier robot. One of the key

modifications was extending the

spectroscopy system.

“The sommelier robot uses mid-

infrared spectroscopic informa-

tion,” said Endo. “Red or white wine

is simply poured onto the sensor.

The robot is also equipped with the

ability to ask questions to determine

a customer’s wine preference.”

The team is now developing the

spectroscopic “tasting” technol-

ogy. “We plan to improve the tast-

ing technology and wish to

commercialize it as a component,”

concluded Endo. “It may be used

for various applications, such as

quality-control, games, dieting

and health applications. We hope

that the wine robot or wine-tasting

machine will be commercialized

by someone in the near future.”

Scientists in Japan have developed a

material that becomes water repel-

lent when it is illuminated with

ultraviolet (UV) light. The proper-

ties of the material mimic those of

the lotus blossom – a flower that is

renowned for being immaculately

clean. What’s more, the effect is

reversible because the material can

be switched back to its original

state using visible light (Ange-

wandte Chemie International Edition

10.1002/anie.200602126).

The secret behind the lotus effect

is a special microstructure on the

plant’s leaves. This forces water

droplets to form beads that roll off

the surface, picking up any dirt par-

ticles that they encounter.

To date, scientists have not been

able to duplicate this natural phe-

nomenon, but now this synthe-

sized material could find uses

wherever a self-cleaning surface is

required. Windows and car body-

work are just two examples.

Kingo Uchida and Shinichiro

Nakamura from Ryukoku Univer-

sity synthesized their material from

a family of compounds known as

diarylethenes. “The thickness of

the film is between 20 and 40µm,”

Uchida told OLE. “When we illu-

minate the surface with UV light at

254 nm from a mercury lamp, fib-

rils start to grow within five min-

utes, but one day later is enough to

observe superhydrophoboicity.”

Uchida and his colleagues switch

the material back to its original

form by illuminating it with light in

the 450–600 nm range. “It takes

only 10 minutes for the material to

return,” commented Uchida.

The infrared sommelier uses spectroscopic analysis to taste red or white wine.

Switchable lotus effect

creates clean surfaces

MATERIALS

The starting point is a 20–40 µm thick film synthesized from a family of compounds

known as diarylethenes (left). When the researchers shine UV light on the surface,

small fibres approximately 1 µm in diameter begin to grow. This creates a super-

water-repellent surface exhibiting the same properties as the lotus blossom (right).

NEC System Technologies

Kingo Uchida, Ryukoku University

OLEOct06TECHNOLOGYp11-17 25/9/06 16:19 Page 12

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response in the near-infrared

TECHNOLOGY

APPLICATIONS

DETECTORS

14 OLE • October 2006 • optics.org/ole

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Researchers are using the same

microstructuring approach that

enhances the efficiency of silicon

solar cells to widen the spectral

response of photodetectors (Appl.

Phys. Lett. 89 033506).

“The challenges lay in under-

standing the material’s physical

properties and how they can be

controlled and used to improve

device performance,” Jim Carey of

Harvard University, US, told OLE.

Conventionally, silicon is trans-

parent to wavelengths longer than

1 µm, which makes it unsuitable for

use in many near-infrared appli-

cations. However, the researchers

have found a way of modifying the

material’s bandgap to make it

absorb at longer wavelengths.

Using a Ti:sapphire laser, Carey

and colleagues irradiated an

n-doped silicon wafer with a 1 kHz

train of 100 fs pulses in a sulphur-

rich atmosphere to generate a sur-

face covered with 2–3 µm-sized

structures. According to the team,

the laser causes ablation and melt-

ing of the silicon surface, which

evolves and interacts with the gas

before re-solidifying with an

altered morphology.

The detector’s microstructured

surface encourages multiple reflec-

tions, which promote the absorp-

tion of light. However, this is only

part of the picture. “It is a combi-

nation of increased absorption in

the infrared [region] and large gain

that leads to the extension of the

operating wavelength,” said Carey.

“The incorporation of large

amounts of sulphur during laser

irradiation is responsible for signifi-

cant absorption beyond 1100 nm.”

Photodetectors made from the

textured silicon were found to have

a responsivity of 92 A/W at 850 nm

and 119 A/W at 960 nm (3 V

reverse bias in both cases). What’s

more, the devices continued to

exhibit a photoresponse at 1.31

and 1.55 µm.

The group, which also includes

scientists from the University of

Texas and the University of Vir-

ginia, both US, is now looking to

commercialize its new technology.

Carey expects that the first big

market will be in specialized ima-

ging applications such as security

and surveillance. He thinks that it

is unlikely that devices will make

their way into consumer items

such as camera phones.

“Margins are too low and the

end customer doesn’t care enough

about the infrared to drive a pre-

mium,” he commented.

Scientists at Rensselaer Polytechnic

Institute (RPI), US, will develop

high-brightness LEDs based on

native GaN substrates from mater-

ials firm Kyma Technologies in a bid

to plug the so-called “green gap”.

While highly efficient blue and

red emitters based on GaN or AlIn-

GaP are routinely made using sap-

phire, SiC or GaAs substrates, the

development of green LEDs has

not been quite so successful.

Now, under the US Department

of Energy’s solid-state lighting core

technologies programme, RPI and

Kyma will work together to produce

improved materials and develop

better processes that should lead to

higher-performance green emit-

ters. The improvement should

result from the use of Kyma’s low-

defect-density native GaN sub-

strates. Both polar and cutting-edge

non-polar materials will feature in

the development programme.

Because they do not suffer from

electric fields in the crystal lattice

that can degrade device perfor-

mance, non-polar LEDs should

have much better performance

characteristics than the conven-

tional polar GaN devices that are

the mainstay of today’s high-

brightness LED industry.

However, initial results with

devices grown on r-plane sapphire

substrates have suffered from a rel-

atively low power output that is

thought to result from high defect

densities in the crystal lattice.

“The use of Kyma’s native GaN

substrates should enable a reduc-

tion of such defects by a factor of

over 10 000 compared with such

non-native approaches,” claimed

the US-based firm.

Kyma’s CTO and co-founder

Drew Hanser will work closely with

Christian Wetzel and Fred Schubert

from RPI’s Future Chips Constella-

tion on the new programme. They

will focus on developing improved,

commercially viable green emitters

that should help to fulfil the promise

of solid-state lighting for general

lighting applications.

Kyma aims to plug ‘green gap’ through DoE project

LEDS

Textured silicon: this scanning electron

micrograph shows the photodetector’s

laser etched surface. The micro-

structures are 2–3 µm in height and are

spaced at intervals of roughly 2–3 µm.

Harvard University

OLEOct06TECHNOLOGYp11-17 25/9/06 16:19 Page 14

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Doubled VECSEL emits

light in the ultraviolet

TECHNOLOGY

R&D

SOURCES

16 OLE • October 2006 • optics.org/ole

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Researchers in the UK have intra-

cavity frequency doubled a 675 nm

vertical external-cavity surface-

emitting laser (VECSEL) to produce

120 mW of ultraviolet (UV) light

at 338 nm. Also boasting a tuning

range of 5 nm, the team believes

that its all-solid-state system shows

promise as a continuous-wave

(CW) rival to nitrogen lasers emit-

ting at 337 nm (Applied Physics Let-

ters 89 061114).

“The advantage of the VECSEL

over conventional solid-state lasers

is that the gain region can be

designed for a specific wavelength

within the constraints of the semi-

conductor material,” researcher

Jennifer Hastie from Strathclyde

University explained to OLE. “Using

AlGaInP quantum wells, it should

be possible to demonstrate red

VESCELs in the 640–690 nm

range, translating to 320–345nm

via frequency doubling.”

Hastie says that the UV VECSEL

has been made possible thanks to

the availability of watt-level CW

power at 675 nm.

The initial red-emitting VECSEL

structure was grown by MOCVD

on a GaAs substrate. It consisted of

a gain region of 20 compressively

strained GaInP quantum wells

separated by AlInGaP pump-

absorbing barriers all grown on

top of an AlGaAs-based distrib-

uted Bragg reflector.

Hastie and colleagues used their

VESCEL structure as the end mirror

in a three-mirror cavity alongside a

spherical folding mirror and a plane

output coupler. The structure was

optically pumped with up to 7 W of

green light at 532 nm yielding

1.1 W of output power at 675 nm.

Inserting a BBO crystal into the cav-

ity produced a maximum UV out-

put power of 120 mW at 338 nm.

Rotating a birefringent filter

within the cavity tuned this output

wavelength over 5 nm centred on

338 nm. “Here we have an all-

solid-state laser with the advantage

of broad gain from the semicon-

ductor gain region,” said Hastie.

“Our 5 nm tuning range is at least

an order of magnitude larger than

that of a trebled Nd:YAG. Also,

most practical UV lasers, including

all-solid-state lasers, are by neces-

sity, pulsed.”

According to Hastie, the current

set-up measures approximately

400 ×150 mm excluding the com-

mercial pump laser. “There is no

reason why it couldn’t be more com-

pact,” she commented. “It should be

possible to diode-pump the VECSEL

once high-power GaN diode lasers

are more readily available.”

The Strathclyde team and its

collaborators are now looking to

improve the efficiency of the second

harmonic generation. “We have no

plans for commercialization at pre-

sent,” concluded Hastie. “This tech-

nology will lead to very practical

sources in application-rich areas so

there are likely to be real opportun-

ities for commercialization as the

technology matures.”

SPECTROSCOPY

Using Fourier transform infrared

(FTIR) spectroscopy in tandem with

pattern-recognition techniques is an

ideal way to obtain the

geographical origin of the Chinese

medicine danshen, according to

Ning Li, Yan Wang and Kexin Xu at

Tianjin University in China (Optics

Express 14 7630).

In Chinese medicine, danshen is

used to promote coronary circulation.

The problem is that the quality of

danshen varies with the growing

conditions in different geographical

regions.“Infrared spectroscopy can

be an excellent candidate for the

determination of danshen origins

because it is fast, accurate, non-

destructive and completely

dependable,” said the authors.

Li and colleagues collected 53

samples from four regions in China.

The samples were pressed into a

tablet, scanned 16 times and

spectra were collected between 400

and 4000 cm–1.

“The results showed that it is

feasible to discriminate [between

samples] using FTIR spectroscopy

ascertained by principal components

analysis [PCA],” concluded the

authors. “An effective model was

built by employing the Soft

Independent Modeling of Class

Analogy and PCA, and 82% of the

samples were discriminated

correctly. Through the use of an

artificial neural network, the origins of

danshen were completely classified.”

JOURNAL WATCH

The intracavity frequency-doubled

VECSEL produces 120 mW at 338 nm

and has a tuning range of 5 nm. The

team believes that the source shows

promise as a CW rival to nitrogen lasers.

Jennifer Hastie, Strathclyde University

OLEOct06TECHNOLOGYp11-17 25/9/06 16:19 Page 16

TECHNOLOGY

R&D/PATENTS

OLE • October 2006 • optics.org/ole

INFRINGEMENT

Toyoda Gosei issues warning over

its blue and white LED portfolio

Toyoda Gosei, the Japanese LED manufacturer,

has advised its competitors to exercise caution to

avoid infringement of its patents covering GaN-

based LEDs. To date, Toyoda Gosei has signed

agreements with its rivals Nichia and Philips

Lumileds that allow the parties to use each other’s

LED-related patents.

The press release goes on to say that “because

the manufacture, sale or use of GaN-based

semiconductor LEDs by any entity other than these

may constitute infringement of Toyoda Gosei’s

patents, Toyoda Gosei advises the fullest caution

to avoid infringement.” The firm says that it has

filed more than 2000 patent applications related

to GaN-based semiconductor LEDs and has

acquired patent rights on 600 of these.

In the same press release, Toyoda Gosei also

issued a warning regarding white-light emitters

that use blue LEDs in tandem with yellow silicate

phosphors. “Toyoda Gosei has recently received

information that companies other than licensees

have been manufacturing and selling white LEDs

using silicate phosphors,” said the firm.

Toyoda Gosei says that there are roughly 20

licensees of this technology worldwide. Again the

firm advised “fullest caution” as non-licensed

entities producing white LEDs using silicate

phosphors may constitute infringement.

APPLICATION

US firm Finisar unveils integrated

source and detector in application

Finisar of the US has integrated a light source

(either a vertical-cavity surface-emitting laser or a

resonant-cavity LED) and a photodiode into a single

device. The invention is detailed in international

patent application WO 2006/073958.

AWARD

UK imaging firm AST receives US

patent for its infrared camera

UK-based Applied Scintillation Technologies (AST)

has been granted US patent number 7075576 for

its compact, low-cost infrared camera

CamIR1550. The product is now protected by both

European and US patents.

“The CamIR1550 uses our specialized

knowledge of phosphor selection and coating

techniques to offer a highly cost-effective

alternative to infrared cameras with specially

processed detectors,” said Stuart Quinn of AST.

“This lightweight portable system has high

sensitivity to 0.2 µJ/cm2and is optimized between

1500 and 1600 nm.”

Typical applications are listed by the firm as

being on- and off-site beam-finding from

communications band emitters; laser alignment of

positioning machines; imaging optical outputs of

high-speed fibre-optics; and device alignment.

LICENSING

Kodak signs up Tohoku of Japan

as licensee of OLED technology

Kodak of the US has signed a licensing

agreement with Tohoku Device of Japan. The

deal will allow Tohoku to incorporate Kodak’s

organic display technology into white OLED

modules for use as backlights in flat-panel-

display applications.

The royalty-bearing licence also includes a

cross-licence to Tohoku’s patent portfolio. It also

gives Tohoku the opportunity to purchase Kodak’s

patented OLED materials. Tohoku joins more than

15 companies that have licensed this organic

technology from Kodak.

PATENTS

To search for recently published applications, visit http://www.wipo.int/pct/en/ and http://ep.espacenet.com.

Scientists have discovered that thin

films of silver – a normally opaque

material – can be made highly

transparent by sandwiching them

between zinc-sulphide-coated glass

blocks. Ian Hooper and colleagues

at the University of Exeter, UK,

said that light passes through the

silver in a way that is similar to

how particles tunnel through bar-

riers. The work could help to

improve the efficiency of OLEDs

and enable a new generation of

semiconductor devices (Phys. Rev.

Lett. 97 053902).

It is well known that light travel-

ing through a solid block will

undergo total internal reflection if

it strikes the surface at a very shal-

low angle. Some of the electromag-

netic field, however, strays into the

air – a so-called evanescent wave.

This can form a beam of lower

intensity if it passes into another

solid block placed nearby. Hooper

and colleagues then wondered

what would happen if each block

was coated with another material.

According to their calculations,

light would be transmitted with

perfect efficiency.

In practice, the researchers

coated the surface of a silica prism

with a film of zinc sulphide just

200 nm thick. They then clamped

two such prisms together, leaving a

very thin air gap sandwiched

between them. When light at the

correct wavelength was used, it

passed through the sandwich with

about 85% efficiency.

The physicists then replaced the

air gap with a 40 nm thick layer of

silver. On its own, silver of this

thickness is almost opaque to light.

But when sandwiched between

the two coated prisms in this way,

the silver was found to transmit

light with an efficiency as high as

35% at certain wavelengths.

According to the researchers,

the light is transmitted because the

reflections from the silica/zinc sul-

phide and the zinc sulphide/silver

interfaces are 180º out of phase

with each other and of equal

amplitude. Therefore they cancel

out to give no net reflection – that

is, all the light is transmitted.

“The reflection from the front

interface combined with the multi-

ple reflections from the subsequent

interfaces also interfere such that

they cancel,” said Hooper. “With

no net reflection and with a non-

absorbing system all the light must

be transmitted.”

The researchers say that their

technique could be used to

improve the efficiency of a new

generation of top-emitting OLEDs,

whose performance is limited by

the light passing through a metal

cathode. It could also be used to

improve semiconductor devices,

where an analogous quantum

effect should be seen.

‘See-through’ silver boosts LEDs

LEDS

Silver lining: light can penetrate silver

metal that is sandwiched between thin,

transparent layers of zinc sulphide and

a pair of prisms (left and right with the

vertical boundary in the centre).

Ian Hooper, University of Exeter

OLEOct06TECHNOLOGYp11-17 25/9/06 16:20 Page 17

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Scanning the lens of a human eye with infrared laser light can reveal the earliest signs of

Alzheimer’s disease in a matter of seconds, according to US start-up Neuroptix. Matthew

Peach speaks to the firm’s chief executive officer, Paul Hartung, about the technology.

Eye scan shows first sign

of Alzheimer’s disease

INTERVIEW

OLE • October 2006 • optics.org/ole

Neuroptix has developed an optical technique

for early diagnosis of Alzheimer’s disease (AD)

– the degenerative illness that is becoming a

growing problem as the population is always

getting older as people are living longer.

Instead of having to wait until a patient shows

signs of mental degeneration, Neuroptix’s

optical technique can indicate the likely onset

of the disease many years earlier, giving a

patient time to make adjustments to lifestyle,

diet and exercise, which could improve their

chances of avoiding the worst aspects of this

currently incurable disease.

The Neuroptix system, known as the QEL

2400, measures the presence of telltale

amyloids in the lens of the eye with a combi-

nation of dye treatment and scanning by an

infrared laser. OLE interviews Paul Hartung,

president and chief executive officer of Neu-

roptix, about the technology.

OLE: What are the origins and

objectives of Neuroptix’s work into

early diagnosis of AD?

PH: Neuroptix was founded in 2001 follow-

ing the breakthrough discovery by our com-

pany founder Lee Goldstein at Harvard

Medical School. He discovered that beta

amyloid proteins, which create plaque in the

brain of patients suffering from AD, can also

be identified in the lens of the eye. Our objec-

tive is to develop and commercialize a non-

invasive eye test for early diagnosis of AD.

Why are you focusing on AD?

AD is now the eighth most common cause of

death (in the US). But this does not represent

the true scale of the problem because AD suf-

ferers often die from other causes. It is also

believed that as we get older the likelihood of

getting this disease increases. It is a devastat-

ing illness not only for the victims, but also for

their families. There is a great need for diag-

nostics to detect the disease at an early stage

and to enable effective treatment. Pharma-

ceutical companies need more sensitive diag-

nostics to striate subjects in clinical trials and

to measure the efficacy of their new therapies.

What is Neuroptix’s test set-up?

Eye drops are applied that contain a fluor-

escent ligand (dye), which is temporarily

absorbed by the lens and binds to amyloid pro-

teins. A low-power class I laser scans the lens,

exciting the fluorescent dye and scattering off

the protein aggregates. The fluorescent dye

provides the biochemical specificity, identify-

ing the type of protein. Using a technique

called quasi-elastic light scattering, we are able

to quantify the size of the protein aggregates.

We can make a judgment on the likelihood of

the patient becoming an AD sufferer based on

the light measurements and post-processing

that data using our software.

In the late stages of the disease, the aggre-

gates in the lens become so dense that they

are visible in the supranucleus of the lens.

Our technique is essentially a molecular

diagnostic technique, with the ability to take

measurements on a clear lens. Pre-clinical

testing has shown that it is sensitive enough

to pick up amyloids in the eye before plaque

forms in the brain.

What is the test timescale?

The test takes a matter of seconds; it is done

within the timeframe of a normal physical

exam. It is similar to, but much less invasive

than, a retinal scan and the equipment is

similar to a laser-scanning ophthalmoscope.

How do you differentiate AD from

other diseases detected this way?

Our dye agent provides the biochemical

specificity of indication for AD. In addition,

there is anatomical specificity based on the

location of the aggregates in the supranu-

cleus of the lens. We are focused on AD but

we believe that it could be applied to prion

diseases. For example, the US Department of

Agriculture is testing this technique to assess

prion-affected deer, sheep etc, using Neur-

optix’s dyes to achieve rapid screening.

What are the limitations of other AD

diagnosis methods?

Clinical diagnosis generally occurs in the

later stages of the disease, based on psycho-

analysis and other factors. The new tests that

are in development include:

Cerebrospinal fluid tests. This requires an

invasive and complication-prone spinal tap

and is not sensitive enough to detect AD;

Brain scans (MRI and PET). These are

expensive and are only of use in the later

stages of the disease. Neuroptix’s technique

will be a feeder technology for these more

expensive tests;

Blood tests. These can only determine

genetic predisposition in some cases;

Urine tests. These have been rejected by

the Food and Drug Administration. They are

not sensitive enough and have highly vari-

able results.

Above: the test, which could be part of a medical

exam, takes a few seconds. Bottom: Paul Hartung,

Neuroptix’s chief executive officer.

NeuroptixNeuroptix

OLEOct06INTERVIEWp19-21 25/9/06 15:48 Page 19

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Project1 22/9/06 14:08 Page 1

How is the Neuroptix’s technique an

improvement on existing methods?

To date there has been no in vivo commercial

biomarker for AD. The “gold standard” so far

has been the mental analysis of a patient, but

by the time that diagnosis is made, the patient

has typically lost 50% neural function – an

irreversible state of brain damage. We can

identify the disease prior to any cognitive

signs developing. Therefore, our aim is to

diagnose the condition prior to any brain

damage occurring.

The potential applications of our tech-

nique will be as an early confirmation test for

AD in those who present with mental prob-

lems and eventually as a preventative AD

check-up technique.

How can an optics-based

assessment help in this endeavour?

Optics-based techniques are suitable for

non-invasive measurement of biophysical

changes to the eye. The methods that we are

developing are non-contact, sensitive, fast

and relatively inexpensive.

What have you achieved in terms of

developing this method?

Initial work has been done using human

cadavers. A preclinical version of the system

has been developed and results show that

the technology is sensitive and can identify

amyloid pathology in the eye at a very early

stage in the disease. Clinical prototypes have

been developed, which are safe for human

use, and it has been proven that in vivo meas-

urements can be performed.

How is this a significant medical

breakthrough and will it save lives?

This is a major medical breakthrough.

Around 4.5 million people in the US are

already diagnosed with AD, with care costs

alone estimated to be $100 bn per year. The

number of sufferers is growing as people are

living longer. The opportunity to catch the

disease prior to cognitive loss, and to enable

early treatment, is enormously significant.

Are there any existing medical

techniques to counter AD?

There are drugs available today that work for

some patients but they are prescribed at a

much later stage in the disease than that

which we are identifying. There are also rec-

ommended lifestyle changes, including bet-

ter diet and physical and intellectual exercise.

On the drug development front, I have to

say that AD therapeutic development is a

high priority for large pharmaceutical com-

panies. There are more than 500 possible

solutions currently under development that

are expected to be fundamentally different

from what is available today. At Neuroptix,

we believe that in the next three years or so

there will be better drugs available.

What are the next stages of

development and are there any

technical or financial barriers?

The next stage of development will be the cre-

ation of instruments for clinical trials and the

safety testing of the fluorescent ligands for

human use. Neuroptix has already raised $1 m

through non-exclusive big pharmaceutical

R&D funds and “angel” investors. We are seek-

ing to raise series A equity financing in 2006.

We are developing partnerships with large

pharmaceutical companies interested in using

the technology as a drug-development tool.

We are also developing partnerships with

medical-equipment and diagnostics compan-

ies to support development, manufacturing

and worldwide commercialization.

Matthew Peach is a contributing editor to OLE and

optics.org.

INTERVIEW

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OLEOct06INTERVIEWp19-21 25/9/06 15:49 Page 21

An optical manipulation and analysis platform that can fit onto a fingernail could signal a

significant change in the field of microfluidics. Simon Cran-McGreehin, Thomas Krauss

and Kishan Dholakia from the University of St Andrews reveal what’s on offer.

Lasers meet fluids: an

integrated approach

OPTICAL TRAPPING

OLE • October 2006 • optics.org/ole

The 21st century could herald a revolution

in the way we perform biological science. Our

aim is to produce microfluidic systems that

analogously provide scientists with the abil-

ity to perform large-scale and parallel auto-

mated studies in the physical sciences –

notably in biology.

Light is the cornerstone for such studies. It

offers a powerful, non-invasive and recon-

figurable way in which to image cellular

samples; induce fluorescence and scatter-

ing; and move and manipulate objects at the

cellular level and below. For lab-on-a-chip

and microfluidic applications, we need to

explore ways to actuate, move and study

small volumes of analyte in extremely small

and confined volumes.

The motivation behind our approach is

simple. To date, physicists have relied on

external macroscopic laser systems and dis-

crete optical components to couple light into

microfluidic platforms to manipulate and

sense micro- and nanoparticles. This intro-

duces problems of alignment and coupling

losses, as well as placing a lower limit on the

size of the apparatus – typically a bench top

is needed for a conventional system.

However, recent work between the Optical

Trapping and Photonic Crystal groups at the

University of St Andrews, UK, bypasses these

issues by combining microfluidics and integ-

rated optics. In our monolithic optical micro-

manipulation and particle sensors, the lasers

are integrated right next to the microfluidic

flows in channels that are less than the width

of a strand of human hair.

Chip layout

Each laser is defined, lithographically, in a

single piece of GaAs-based laser material giv-

ing perfect intrinsic alignment. Microfluidic

channels are then fabricated directly on top

of the laser material, allowing the light to

couple directly into the sample without the

need for additional optics. This drastically

reduces the size of the system, making it

portable and simple to incorporate into exist-

ing microscope systems.

Both the concept and device design are

fairly simple. We believe that any research

group with access to semiconductor pro-

cessing facilities could replicate the device

using materials costing just a few pounds.

Indeed, we hope that this technology can be

spread rapidly among the biophotonics

community, giving access to the advantages

of optical methods without the need for spe-

cific optics knowledge.

The aim is to make the device as user-

friendly and robust as possible. Care has also

been taken to avoid any problems arising

from sending lasers in and out of the ports of

a microscope system. To this end, the device is

mounted onto a circuit board and the lasers

are wire-bonded to copper tracks, which in

turn are connected to a power supply.

The optical power of each laser is controlled

by varying the applied voltage (and hence cur-

rent), up to a maximum of around 20 mW at

about 3 V (approximately 200 mA). Such

electrical powers can be provided by a com-

puter interface board, opening up the way for

automated operation.

Fabricating the device

The starting point is a GaAs chip, typically

6×6 mm. The actual device is dominated by

2 mm-long lasers that determine the surface

area of the chip.

At the heart of each laser is an AlGaAs/

GaAs singlemode heterostructure, centred

1 µm beneath the chip’s surface. Grown epi-

taxially by German firm Nanosemiconductor

of Dortmund, the structure provides vertical

waveguiding and contains InAs quantum

dots that emit at 1290 nm.

Horizontal waveguiding is provided by

etching away the GaAs to leave a ridge 3 µm

wide and 750 nm deep that supports only a

single vertical transverse mode. An electri-

cal current is injected into the ridges via gold

contact pads and SU8-2000 polymer insu-

Miniature manipulator: the entire system, including fluid injection and electrical connections can fit into

the palm of a hand. At the heart of the device is a GaAs chip (inset) that measures only 6 ×6 mm.

University of St Andrews

OLEOct06INTEGRATEDp23-25 25/9/06 15:45 Page 23

OPTICAL TRAPPING

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24 OLE • October 2006 • optics.org/ole

lation on the etched GaAs confines the cur-

rent to the ridges where a useful optical

mode is generated.

The length of the laser cavity is defined by

facets that are etched to a depth of at least

2 µm. The tight vertical confinement of the

heterostructure leads to large vertical diver-

gence of the output beam, up to as much as

40˚, so the optical power density falls off

quickly with distance from the facet.

Of greatest interest is the interface between

the lasers and the fluids. The microfluidic

channel is etched into the GaAs at right

angles to the lasers and passes between pairs

of facing lasers. This allows the laser beams to

enter from both sides of the channel to give a

dual-beam trap configuration.

The electrical activity of the lasers is insu-

lated from the fluid by lining the microfluidic

channels with SU8-2000 polymer. A thin

layer covers the base and a thicker layer lines

the walls, essentially determining the depth of

the channel. A glass lid is then adhered to the

top of the chip and sealed with adhesive to cre-

ate a watertight microfluidic channel that can

be fabricated in any desired configuration.

The size and position of the features can be

tailored to the application. The facet spacing

determines the optical power at the centre of

the microfluidic channel where facing

beams overlap. Closer facet spacings give

higher power densities resulting in stronger

trapping and larger detection signals.

Meaningful optical forces are exerted up to

around 200 µm from the facets, placing an

upper limit on their spacing. The lower limit

on the facet spacing is determined by the

resolution of the current photolithographic

techniques that define the SU8-2000 lining

on the walls. This places a lower limit of

about 20 µm on the facet spacing.

Typical microfluidic channels measuring

30 µm high and 40 µm wide, with a facet

spacing of 75 µm, allow the passage of biolo-

gical cells. The channels can be arranged in

various configurations, ranging from straight

channels to junctions for sorting and cham-

bers for mixing. Using water or biological

buffer solutions in the microfluidic channels

provides a medium in which particles can

flow into the paths of the laser beams.

Applications

Using a single laser, we have guided particles

over ranges of around 200 µm. Essentially,

the gradient force draws objects onto the

optical axis and the radiation pressure

pushes them away from the facet.

Pairs of facing lasers have been used to cre-

ate dual-beam traps, in which the objects are

held at the equilibrium point between the

two facets. Once trapped, particles can be

interrogated. We have demonstrated fluor-

escence spectroscopy in this configuration

and Raman spectroscopy is an obvious can-

didate for future studies.

Useful operations are possible even when

the optical powers are insufficient to trap

particles. This has led to the development of

two detection methods, both of which make

use of the fact that facing lasers feed light

into one another.

Trapping trio: (from left to right) Kishan Dholakia, Simon Cran-McGreehin and Thomas Krauss

demonstrate their versatile optical manipulation and analysis platform. The integrated module’s 50 µm-

wide trapping channel can be seen on the monitor as a bright stripe running across the middle of the

screen. Lasers located at either side of the channel are used to push and trap particles.

University of St Andrews

OLEOct06INTEGRATEDp23-25 25/9/06 15:45 Page 24

In the first method, the output power of

one laser is found to decrease when a particle

passes between the facets. In the second, one

laser is reverse-biased to create a photo-

detector whose photocurrent decreases

when a particle passes by.

These methods use the intrinsic properties

of the semiconductor lasers and require no

external light source – the second method

requires no external optics whatsoever. We

now plan to combine these operations into

more complex arrangements in which the

particles are moved around a device, either by

optical forces or by an externally generated

fluid flow, to different interrogation sites.

A look to the future

As a first step, this new technology makes the

power and versatility of optical manipula-

tion more widely available by simplifying the

operation and reducing the cost. We believe

that this technology lends itself to the world

of lab-on-a-chip, in which miniaturized test

and measurement systems are integrated

into microfluidic circuits.

By configuring the lasers and channels in

order to usefully combine the functions of

guiding, trapping and detection, a wide variety

of multiplexed processes could be conducted,

in parallel, on a single chip. This range could be

extended further by using external analysis

techniques such as Raman spectroscopy.

A more compact approach would modify

the laser material to allow the direct, on-chip

excitation and detection of fluorescence in

particles, such as violet-emitting GaN-based

material in conjunction with green fluor-

escent protein. The technology could also

have a use in the realm of atom optics, cre-

ating dipole traps that could hold Bose–Ein-

stein condensates.

Thomas Krauss heads the Microphotonics and

Photonic Crystals group and Kishan Dholakia

leads the Optical Trapping group at St Andrews

University, UK. Simon Cran-McGreehin is a

research assistant working in both groups. For

more information, including links to optical

trapping groups worldwide, please see www.st-

andrews.ac.uk/~atomtrap/.

OPTICAL TRAPPING

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guide laser

trapping lasers

Concept diagram showing particles being pushed

and trapped by integrated lasers.

OLEOct06INTEGRATEDp23-25 25/9/06 15:46 Page 25

The attractiveness of zinc oxide (ZnO) LEDs

stems from the potential for phosphor-free

spectral coverage from the deep ultraviolet

(UV) to the red, coupled with a quantum effi-

ciency that could approach 90% and a com-

patibility with high-yield low-cost volume

production. One day these LEDs could even

outperform their GaN-based cousins (which

offer a narrower spectral range) thanks to

three key characteristics – superior material

quality, an effective dopant and the availabil-

ity of better alloys.

The superior material quality is seen in the

low defect densities of ZnO layers. At MOX-

tronics, our development of a viable p-type

dopant has provided hole-conducting layers

for ZnO-based devices. And our growth of

BeZnO layers has shown that it is possible to

fabricate ZnO-based high-quality hetero-

structures (see box “The advantages of ZnO

over GaN” p27).

ZnO also promises very high quantum effi-

ciencies, and UV detectors based on this mat-

erial have produced external quantum

efficiencies (EQE) of 90%, three times that of

equivalent GaN-based detectors. The physical

processes associated with detection suggest

that similarly high efficiency values should be

possible for the conversion of electrical carri-

ers to photons. So it is plausible that ZnO LEDs

will have an EQE upper limit that is three

times higher than that of GaN-based devices.

Finding the right dopant

However, ZnO is yet to fulfill all of its promise

because of the delay in developing p-doped

material. Early progress throughout the

community was hampered by focusing

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Nitrogen was the first choice because it was

an effective dopant in ZnSe, and also because

it was deemed, erroneously, to be of a suit-

able size to sit on an oxygen lattice site.

Although we also tried to obtain p-type

doping using nitrogen, a switch to arsenic

enabled us to report the first successful

p-type doping of ZnO in 1997. By 2000 we

could produce hole concentrations into the

1017 cm–3 range with this approach.

Later in 2000 we reported our hybrid

beam deposition (HBD) process that offers a

viable approach to growing doped and

undoped ZnO films, alloys and devices. The

HBD process is comparable to MBE. However,

it uses a ZnO plasma source, which is pro-

duced by illuminating a polycrystalline ZnO

target with either a pulsed laser or an elec-

tron beam, and a high-pressure oxygen

plasma created by a radio-frequency oxygen

generator. Additional sources for either dop-

ing or ZnO-based alloy growth can be added

to the growth chamber by conventional

evaporation or injection methods.

We used the HBD process to fabricate the

first ZnO-based UV detectors (see box “Highly

efficient detectors” p27), UV LEDs, FETs, and

red, green, blue and white phosphor-coated

LEDs. Our LEDs incorporate BeZnO, an alloy

that allows bandgap engineering into the UV

and the formation of multiple quantum

wells and other heterostructures.

Why BeZnO beats MgZnO

BeZnO alloys of varying composition have

significantly boosted the development of our

deep UV high-power LEDs. These alloys do

not phase-segregate, because BeO and ZnO

have the same hexagonal crystal structures,

and the extremely high-energy bandgap of

BeO could potentially lead to devices emitting

at just 117 nm. UV LEDs containing BeZnO

alloys produce a narrow spectral profile, with

very little emission in the visible, suggesting

that the alloy is of high crystal quality.

Until we had produced BeZnO films, the pri-

mary choice for a compatible higher bandgap

alloy was ZnMgO, a material developed by a

group at Tohoku University, Toyo University,

Tokyo Institute of Technology and Japan’s

Institute of Physical and Chemical Research.

In 1997 this team reported that crystal phase

separation occurs between MgO and ZnO

when the atomic fraction of magnesium

exceeds 0.33, which corresponds to a bandgap

of 3.99 eV. The separation is driven by differ-

ent crystalline structures; MgO is a cubic

structure with a lattice spacing of 0.422 nm,

while ZnO is a hexagonal wurtzite structure

with a lattice spacing of 0.325 nm.

We recently produced and characterized the

first UV LEDs made from ZnO and BeZnO. The

device’s emission can be tuned from the deep

UV to around 380 nm, the wavelength associ-

ated with ZnO. Our devices have been built

with several different active layer structures,

including double heterostructures and single

or multiple quantum wells, to try to improve

efficiencies and optical output powers.

Our latest UV LEDs have a typical wall-

plug efficiency of 0.1%, which would equate

to an efficacy of 0.6 lm/W if the emission

were in the visible spectrum. Although the

efficiency is far lower than that of GaN LEDs,

we are making rapid progress by addressing

the various phenomena that degrade device

performance. If progress continues at the

same rate we will produce LEDs with a 1%

wall-plug efficiency within one year, 1–5%

within two years and about 10% or more

within three years.

Our ZnO LED development programme

has used various substrates manufactured

by several vendors and has shown that the

LED’s performance is directly dependent on

the substrate’s material type and crystalline

quality. Single-crystal ZnO produces the best

devices. This material has been available for

Start-up company MOXtronics has recently produced the

first coloured ZnO-based LEDs. Although the efficiency of

these LEDs is not high, improvements are rapid and the

emitters have the potential to outperform their GaN rivals,

say Henry White and Yungryel Ryu from MOXtronics.

ZnO-based LEDs begin to s

OPTOELECTRONICS

26 OLE • October 2006 • optics.org/ole

MOXtronics has recently produced the first-ever ZnO-based LEDs emit

to its devices. Further development of ZnO-based materials could lea

MOXtronics

OLEOct06ZNOLEDSp26-27 25/9/06 16:21 Page 26

many years and interest is rapidly increasing

for the growth of high-quality single-crystal

ZnO with a diameter of 50 mm or more or

ZnO-based LEDs and other devices.

What’s needed

Major improvements in the efficiency and

power output of ZnO UV and visible LEDs are

still needed to enable these devices to compete

in the market-place. Advances will depend on

the availability of higher-quality single-crys-

tal substrates and improved processes for pro-

ducing reliable and highly ohmic electrical

contacts to various different layers. Addi-

tional bandgap engineering development is

needed for the UV C-band (100–280 nm) and

visible region, along with optimization of the

multiple quantum well and related structures

in the device’s active region.

Looking ahead

With the output power of our ZnO LEDs

increasing rapidly, these devices appear to

have a promising future. We expect them to

first be deployed in white-light lamps and

replace incandescent sources in applications

such as liquid-crystal display backlights. The

promise of emission from the UV through

the visible will then allow ZnO LEDs to target

applications where no other single semicon-

ductor material can operate today. At this

time, for example, red–green–blue sources

that are fabricated on a single wafer will offer

unique advantages for the development of

bright, compact displays and projectors.

Laser diodes built from ZnO-based materials

could also be produced that emit in the vis-

ible and UV and offer compact alternatives

for larger tube-type laser sources, ushering

in a new era for colour printing.

Yungryel Ryu (ryuy@moxtronics.com) is

president and CEO of MOXtronics. Henry White

(whiteh@ moxtronics.com) is chair of the

MOXtronics board and a professor at the University

of Missouri, MO, US. Both were members of the

company’s original start-up team. MOXtronics Inc

was formed in December 2000 as a spin-out

company of the University of Missouri. The firm

has obtained funding from both the Office of Naval

Research and NASA, and also through equity sales.

This article originally appeared in the August issue of

Compound Semiconductor magazine.

OLE • October 2006 • optics.org/ole

show full-colour potential

The three major benefits of ZnO over GaN are:

superior material quality, which has been

demonstrated by the growth of high-purity ZnO

with defect densities below 105 cm–2, a value

typically associated with the best GaN films;

improved doping performance, which results

from the arsenic p-type dopant that has an

activation energy of 119 meV in ZnO films, far

less than the 215 meV for magnesium-doped

p-type GaN. This lower activation energy

produces a 10-fold increase in the proportion

of activated acceptor atoms that are needed for

electrical conduction (assuming the same

atomic dopant concentrations are used) and

also reduces the number of defects for a given

hole carrier density;

the availability of better alloys, due to our

recent development of high-quality BeZnO films.

These layers have driven the fabrication of LEDs,

lasers and transistors that have less disorder

than the structures produced using the

AlGaN/GaN material system. The reduced

disorder is a consequence of the large

difference in bandgap between ZnO and BeO,

and enables only small changes in the alloy’s

composition to produce relatively large changes

in bandgap. In comparison, a much larger shift

in aluminium composition is required to

produce the equivalent changes in AlGaN and

this leads to greater disorder. The ZnO-based

material system could also be extended into the

visible using alloys such as CdO, CdSe and CdS.

The advantages of ZnO over GaN

MOXtronics has also developed the first UV

detectors based on ZnO. The sensitivity of

these devices is three times higher than that

of any other UV solid-state detector and they

have a responsivity of 0.27 A/W at 372 nm

(see figure, right). The detector’s noise floor at

visible wavelengths is four orders of

magnitude lower than its response in the UV,

making it an attractive option for visible-blind

applications. The device’s temporal response

is typically 50 µs, but it can be shortened

considerably and approach the theoretical

limit of 10 ns by optimizing the structure and

the electrodes’ dimensions.

MOXtronics expects to develop high-speed

focal-plane arrays, with pixel dimensions of

typically 128 ×128, by the end of next year.

These arrays, and single-element detectors,

should become important components in both

portable UV spectrometers and in the ultrafast

UV spectrometers designed for the analysis and

temporal de-convolution of fluorescence spectra.

Highly efficient detectors

s emitting in the white, red, blue and green, by attaching phosphors

ld lead to phosphor-free ZnO LEDs serving all these colours.

wavelength (nm)

responsivity (A/W)

100

200 300 400 500 600 700

10–1

10–2

10–3

10–4

UV visible

MOXtronics’ highly sensitive UV detectors have a

very fast response time and can analyse the change

in fluorescence spectra over very short timescales.

OLEOct06ZNOLEDSp26-27 25/9/06 16:21 Page 27

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Evatec – delivering new components, new

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OLEOctAdverts28 20/9/06 09:02 Page 1

There is a lot more to making an optical filter than meets the eye. Dominik Goessi looks

at the role of in situ monitoring in the production process and reviews the technology.

In situ method drives up

yields and reduces costs

OPTICAL MONITORING

OLE • October 2006 • optics.org/ole

The humble interference filter often plays a

critical role in optical experiments. Made up of

tens of layers, each one precisely deposited and

monitored, there is certainly a lot more to this

standard component than meets the eye. Its

manufacture typically involves in situ mon-

itoring and control systems to minimize pro-

duction time and cost, and to maximize yields.

Enhanced electron-beam deposition pro-

cesses such as reactive low-voltage ion plating

(RLVIP) are ideal for producing complex opti-

cal filters with 50 layers or more. These tech-

niques can generate thin films with high

density, high-temperature stability and a min-

imum of absorption. However, expensive coat-

ing materials, long process times and costly

substrates, that cannot always be reworked in

the event of an error in the coating process,

mean that monitoring is essential.

Monitoring techniques

Thin-film deposition processes are typically

controlled by one of two techniques: quartz

or optical monitoring.

Quartz crystal is the most commonly used

monitoring system. Here, an oscillator

excites a quartz crystal to high frequencies of

around 5 MHz. When the crystal is coated, its

frequency decreases and this change gives a

measure of the film’s thickness.

On the plus side, the hardware is relatively

inexpensive and easy to operate, and is used

successfully in many semiconductor and opti-

cal applications. However, the monitoring sys-

tem is not optimal for complex optical coatings

because the layer thickness on the substrate or

on a test glass is not measured directly.

Optical film-thickness measurements rely

on the fact that the intensity of a mono-

chromatic light beam reflected by a film

changes periodically with increasing film

thickness. The technique has the advantage

that a film’s optical properties are measured

directly using test glasses, which can then

be kept and checked for process and quality

control. However, the initial hardware

investment and set-up costs are higher than

that of crystal monitoring.

To compare quartz crystal and optical mon-

itoring systems, 15 samples, each having an

identical two-layer sequence of high and low

refractive index materials, were coated in an

Evatec BAP800 evaporating system.

The reproducibility of the layer density

using RLVIP on a BAP800 system is very

good, so one would expect the quartz crystal

to give the same thickness result for each

sample. However, results varied between

24.1 and 25.2 nm for the first layer and

between 54.0 and 56.2 nm for the second

layer. This highlights the reduced control of

quartz monitoring.

In practice, it is possible to correct coating

errors with crystal monitoring for designs

with approximately 10 layers. However, for

coatings with 20, 30 and 50 layers or more,

the error within each layer is unacceptably

large with insufficient reproducibility to

achieve the highest yields. A more precise

monitoring system is required.

Optical approach

Deposition processes such as RLVIP in com-

bination with optical monitoring systems are

therefore ideal for manufacturing complex

interference filters with high accuracy and

reproducibility. The theory and practice are

well matched. The actual spectral curves

achieved are identical to the calculated ones,

proving that optical monitoring systems jus-

tify their higher initial investment and set-up

costs through better process control and

higher yields.

An optical monitoring system has two

senders: one for transmission and another for

reflection measurements. The receiver is the

same for both modes of operation. White

light reflected from, or transmitted through,

a test glass passes through a monochromator

before being focused onto a detector. The sig-

nal from the detector is then fed into a lock-in

amplifier where it is processed and digitized.

Consider a test glass with a refractive index

of nGthat has already been coated with a film

of thickness dand refractive index nL. In

reflection mode, for example, a light beam

from the sender (R) hits the coated test glass

and is refracted and partially reflected (R1)

when it enters the optically thicker medium.

The refracted light reaches the interface

between the film and the test glass after it has

passed through the optical film thickness nLd.

One part of the light is reflected (R2) and the

other part penetrates the test glass. The

reflected light passes back through the film

again and multiple reflections occur at the

interfaces. The intensity of the reflected light

decreases continuously but the intensity of

the individual reflected light beams add

together to give the total intensity.

When monochromatic light with the wave-

Production benefits: optical monitoring systems give manufacturers a high level of process control.

Evatec

OLEOct06EVATECp29-30 25/9/06 14:39 Page 29

length hcrosses the interface from optically

thinner to thicker material, the reflection is

also accompanied by a phase shift of h/2. The

phase difference of reflected or transmitted

light is determined by the difference in optical

path lengths 2nLdand the phase shift that

occurs at the interfaces. We can therefore see

a turning point in the total intensity curve of

superimposed, reflected monochromatic light

beams depending on the light wavelength, the

refractive index and the instantaneous thick-

ness of the coated material.

In practice, as the film thickness increases

continuously during the coating process

itself, the turning point condition is fulfilled

at regular intervals and the intensity of the

reflected light beam detected at the receiver

reaches various maxima and minima with a

periodic structure. The distance between the

turning points depends on standard vari-

ables including evaporation rate r. If the

evaporation rate and the refractive index of

the film material are known, then it is poss-

ible to monitor film thickness using the

intensity curve measured at the receiver. A

special cut-off algorithm is used to control

the coater and terminate evaporation when

the desired film thickness is reached.

Successive manufacturing runs for a typ-

ical edge filter consisting of 24 optimized lay-

ers in an Evatec BAK760 with the optical

monitoring system GSM1100 demonstrate

the level of production control that can be

achieved with optical monitoring. The spec-

tral transmission curves for three batches

with 50% transmission values of 653.5,

651.5 and 652.8 nm respectively show an

excellent reproducibility of ±1nm.

The future of optical monitoring

A new generation of fast CCD image sensors

specifically designed for low-light-level detec-

tion in combination with an imaging spec-

trograph enables the precise monitoring of a

whole spectral range (broadband monitor-

ing). The coating process can be controlled by

direct measurement on the substrate and the

whole optical spectrum of each layer is

known and can be controlled. This means

that even in the event of a coating error mid-

process, the remaining layers can be recalcu-

lated in situ to give the correct end result.

Currently, the sampling frequency of these

set-ups is lower than those used in mono-

chromatic monitoring. As a result, special

algorithms are required to terminate a coat-

ing process precisely between two measure-

ments. However, given the rapid progress in

the quality and speed of CCD sensors, the

future of optical monitoring systems looks

set to become broadband.

Dominik Goessi is a physicist with a special

interest in the development of optical monitoring

systems. He works in Evatec’s development

laboratory at the company’s manufacturing facility

in Flums, Switzerland. See: www.evatecnet.com.

OPTICAL MONITORING

30 OLE • October 2006 • optics.org/ole

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OLEOct06EVATECp29-30 25/9/06 14:40 Page 30

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OLEOctAdverts32 26/9/06 08:41 Page 1

Thanks to a set of unique properties, diffractive optical elements have the potential to

transform light into almost any desired distribution. Joshika Akhil gives the low-down on

the technology that can benefit laser marking, material processing, heat treatment,

sensing, non-contact testing and optical metrology, to name just a few applications.

Hybrid diffractive optics

offer an elegant solution

PRODUCT GUIDE

OLE • October 2006 • optics.org/ole

Diffractive optical elements (DOEs) can mod-

ify laser beams in almost all of the same ways

as conventional refractive optics, but with

the added attraction of beam manipulation.

Elements such as beam homogenizers, dif-

fusers, beam samplers, diffractive focal

lenses, beam splitters and various grating

structures can transform light into almost

any desired distribution. Furthermore, the

modulation of light is not limited to laser

beams – DOEs can be used to modulate par-

tially and non-coherent light sources as well.

User benefits

DOEs have the unique ability to transform

the original beam into a variety of shapes,

distributions and numbered spots without

unduly affecting the output intensity of the

entire system. One of their greatest advant-

ages is that a single optical element can often

replace multiple optical systems to customize

the beam profile to the desired shape and

intensity distribution.

Recent developments in design and process

control now allow DOEs to be manufactured

in a compact, reliable and cost-effective way.

Using lithographic techniques, a microrelief

diffraction grating can be etched into the opti-

cal element to create a single optical device.

Diffractive optics redistribute the energy

between the centre and the periphery of a

laser beam, making them ideal for beam

shaping (figure 1). Beam homogenizers

smooth out the intensity profile of an inci-

dent beam and suit applications such as laser

ablation and heat treatment, where hot spots

within the beam are undesirable.

Traditionally, beam homogenizers have

been restricted to operation within the focal

plane of a lens (spot operation) or have a min-

imum working distance. If operated outside of

these conditions, undesired peaks can appear

in the distribution. However, there is a new

device on the market that is less sensitive to

positioning, called an HM-type homogenizer.

Beam shapers create specific energy-distri-

bution patterns with sharp edges. The basic

technique involves remapping the intensity-

distribution profile of the incident beam into a

uniform spot distribution of a specific size and

shape, and at a specific distance. In principle,

any transverse spot shape can be obtained,

although the most useful geometries are typ-

ically round, rectangular and square. Adding

a lens to the diffractive element shifts the loca-

tion and changes the scale of the distribution,

tailoring it to specific applications.

One great advantage of the so-called dif-

fractive top-hat beam shaper over other uni-

form illumination systems is that it eliminates

the trade-off between efficiency and spot uni-

formity by diffractively redistributing the

beam energy. Other techniques can simply

block out a significant part of the energy.

Users should remember that to achieve out-

standing results, the incident beam must have

a collimated Gaussian profile and be centred

on the element. Beam expanders and spatial

filters can be used to optimize the input beam.

Important role

Top-hat intensity distributions suit appli-

cations where a controlled transfer of energy

at the spot is essential, particularly in pro-

cesses that have an exposure level and dam-

age threshold for a given power density.

Examples include raster-scan-picture gener-

ators and high-power laser treatments in mat-

erial processing and medical applications.

As a result, DOEs are proving to be an

essential component in industry sectors such

as laser ablation; welding and drilling; med-

ical and aesthetic lasers; and laser displays.

The uniform-intensity spot, steep transition

region and sharp profile offer unmatched

manageability and accuracy.

However, beam shaping is not limited to

simply a top-hat output intensity profile. Cus-

tom optical elements can be manufactured to

give various spot shapes and intensity distri-

collimated Gaussian

incident beam from

laser and expander

plano-convex lens

diffractive pattern

top-hat spot

Dout

Dinc, 1/e2

incident beam intensity distribution output profile – after transformation

Fig. 1: top-hat beam shapers can deliver outstanding results, transforming a near-Gaussian incident laser beam into a uniform-intensity spot.

OLEOct06PRODUCTGUIDEp33-35 25/9/06 16:06 Page 33

butions while maintaining high efficiencies.

Conventional lenses generate focused

spots, whereas a diffractive focusing ele-

ment can provide the required caustic line

in the focal plane (figure 2). Using a plano-

convex lens as the focusing element with a

diffractive microrelief pattern on its plano

surface, the DOE directs laser light towards

the line contour (straight line, ring, poly-

gons etc) instead of at a single focal spot.

Thus, a line-contour focal image is achieved

from the collimated laser beam without any

scanning system.

The line-contour focusing element provides

novel opportunities in laser marking, drilling

and in the welding of plastics and metals

using high-power lasers. Applications also

exist in machinery and microelectronics; the

optical heads of scanning laser writers; opti-

cal information processing; and laser surgery.

Splitting and multiplication

Recent advances in diffractive optics theory

and technology have made beam splitting/

multiplication a valuable resource for optical

designers. Applications range from spot-array

generation and fibre-optic coupling through to

laser heat treatment of material surfaces and

laser ablation. Other promising opportunities

for the technique include multiple and multi-

focal imaging, laser-beam mode selection and

simultaneous contour shaping.

Diffractive beam splitters have been widely

used in laser perforation as they allow high

throughput and accurate positioning, with-

out leaving any working residual materials

(figure 3, p35). By integrating diffractive

beam splitters into these systems, several per-

forations can be achieved simultaneously

with extremely accurate distances between

the spots, removing the need for a moving

x–ytable and improving performance.

Multiple-spot (including double-spot) DOEs

provide a line or an array of identical focal

spots located in the focal plane and can be

arranged in a one or two-dimensional pat-

tern. DOE beam splitters offer advantages

including uniformity in power between the

spots (±1% can be achieved for standard 1 ×

2 and 2 ×2 splitters and significantly more

for other designs). The positional predictabil-

ity of each beam/spot is also enhanced.

Beam sampling

Another DOE closely related to the beam split-

ter is the beam sampler, which enables inline

measurements of high-power laser beams to

be made. The device produces two exact

copies (samples) of the input beam with only

a small fraction of the total power, while the

main part of the master beam continues in

the optical train. This allows the sample

beams to be measured and analysed while the

main beam remains unaffected and opera-

tional. Beam samplers can be produced to

suit custom angles, wavelengths and various

power fractions of the main beam.

Diffractive beam samplers are being used

in place of conventional optics more and

more, because they offer a clean, non-inva-

sive analytical solution. For example, they

are replacing burn-off modal measurements

for CO2lasers. Since there are no burning ele-

ments in the system, no by-products are pro-

duced. Also, the diffractive beam samplers

are not polarization dependent and so meas-

urements can be taken while the laser is

operating online.

Diffractive beam samplers can be used to

monitor high-power CO2, Nd:YAG and other

lasers in materials processing, medical appli-

cations and in laser radar systems.

A single diffractive corrected focusing lens

can equal the high performance of a complex

multiple-optical-element objective lens. The

Leister ProcessTechnologies

Axetris Microsystems Division

Switzerland

Phone +41 41 662 74 74

axetris@leister.com

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Laser diode collimation

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PRODUCT GUIDE

34 OLE • October 2006 • optics.org/ole

L0L

I0I

I0,^0I0,^

Fig. 2: Schematic view of a line contour set-up (left) and the corresponding output pattern (right).

“DOEs can

modulate partially

and non-coherent

light sources as

well .”

OLEOct06PRODUCTGUIDEp33-35 25/9/06 16:07 Page 34

diffractive microrelief pattern on the plane

side of the lens gives a diffraction-limited spot

size that demonstrates a sharp focusing effect

and a dramatic increase in power densities,

even for long focal length DOEs.

Diffractive corrected focusing lenses offer

unique properties not matched by conven-

tional optics. “Special effects” include off-axis

sharp focusing; control of the focal spot

shape; controlled introduction of spherical

aberration; longer depth of focus; chromatic

correction; and double (multiple) spot focus.

Combining two beams

Many medical CO2(10.6 µm) laser systems

use a red He:Ne (632.8 nm) laser or laser

diode (635 nm) module (LDM) to generate

an aiming or pilot beam. It is essential that

the visible He:Ne/LDM beam coincides with

the invisible CO2beam so that the CO2focal

spot can be easily identified. Conventional

methods often use lens doublets and crys-

talline optics such as potassium bromide ele-

ments, which are hygroscopic and relatively

inconvenient to work with.

An elegant solution to this problem is a sin-

gle hybrid diffractive element called a dual-

wavelength beam combiner. This is a zinc

selenide lens with a microrelief diffraction

pattern etched into the plane side. The dif-

fractive pattern can be designed to control

just one wavelength. When placed in the path

of the 10.6 µm and 633 nm laser beams the

DOE superimposes both wavelengths at the

same focal spot, without the need of doublets.

The durability of the diffractive beam

combiner far exceeds the two-lens system

alternative. Also, the integral light trans-

mittance of the diffractive dual wavelength

element outperforms any on-axis reflective

systems, with figures exceeding 98%.

Joshika Akhil is technical sales engineer at Laser

Components (UK) Ltd. For more information, see

www.lasercomponents.co.uk.

PRODUCT GUIDE

OLE • October 2006 • optics.org/ole

The natural

selection for

ti:sapphire

pumping.

Now available at 6 Watts, the finesse

from Laser Quantum is the smart

choice for optical pumping applications.

Noise <0.5% rms; stability <1.0%rms;

automatic power control; 22,000 hour MTBF

diode life; no external cooling; proprietary

DEP cavity design; compact and robust

construction; advanced PSU with large LCD

and intuitive controls; remote interlock;

RS232 interface.

the evolution of technology

t: +44 (0)161 975 5300 f: +44 (0)161 975 5309

www.laserquantum.com

sales@laserquantum.com

incident

beam

mask

rotating web

in focal plane

lens

DOE

Fig. 3: the beam splitter DOE accepts a collimated

beam and produces a number of beams with the

same characteristics as the incident beam except

for angle of propagation and power. By placing a

focusing lens close to the element, all beams can

be focused into spots. A mask is recommended for

blocking higher order diffraction fringes.

OLEOct06PRODUCTGUIDEp33-35 25/9/06 16:08 Page 35

machine

vision

enquiries

than ever

before.

Mark Williamson, Firstsight Vision, IPOT 2006

To find out more call Marlene Carr on +44 (0)1822 614671

or email: mc@trident-exhibitions.co.uk or visit the web @

www.ipot.co.uk

supported by

PLUS IPOT, Machine Vision & Displays Technology is co-located alongside: Mtec (Sensors,

Measurement & Instrumentation);Machine Building; Practical Vacuum;MDT and 3C

NEC,Birmingham, UK, 14 & 15 February, 2007

www.photon-energy.de

 Nd - Lasers  Diode pumped  Arclamp pumped

 Application: Marking-Structuring-Cutting-Welding

 Designed for industrial environment

 Frequency:

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up to TEM

Photon Energy GmbH

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Fax: +49 - 9123 - 99034 - 22 www.photon-energy.de

E-Mail: info@photon-energy.de

LASERSOURCES

•Scintillation crystals •Linear & two dimensional arrays

•Detector assemblies •Infra-red optics •Custom products

Crystal

Materials

Westwood, Margate, Kent CT9 4JL, UK

Tel: +44(0)1843 231166

Fax: +44(0)1843 290310

email: sales@hilger-crystals.co.uk

www.hilger-crystals.co.uk

www.newport.com

OLEOctAdverts36 22/9/06 13:29 Page 1

Oscilloscope

Tektronix

Test and measurement

specialist Tektronix has

released the

DPO70000 digital

phosphor oscilloscope

and the DSA70000

digital serial analyser.

According to the firm, these new 4, 6 and 8 GHz

bandwidth instruments provide industry-best

hardware and software for data-acquisition,

debug, validation and compliance testing.

With a sample rate of 25 GS/s on all four

channels simultaneously, the new models are

said to provide the fastest four-channel sample-

rate performance of any oscilloscope available.

For example, the 8 GHz DPO70804 and

DSA70804 have a typical rise time of 35 ps and

provide a jitter noise floor down to 400 fs rms

(typical) for critical jitter measurements. The

DPO70000 offers 10 million data points as

standard per channel while the DSA70000

offers 20 million as standard per channel.

www.tektronix.com

Tunable filter

Yenista Optics

Yenista Optics of France has unveiled a low-loss

tunable filter. The device is said to tune over

120 nm from 1510 to 1630 nm with a full

spectral sweep time of 200 ms, an

autopositioning wavelength accuracy of 2 pm,

PDL of maximum 0.2 dB and insertion loss of

3 dB. Yensita adds that the 3 dB bandwidth of

the filter is 0.35 nm although other bandwidths

are available on request. The product is offered

in rack-mount and benchtop versions for test

and measurement applications in the laboratory

as well as in the field.

www.yenista.com

Laser welding system

ROFIN Laser Micro

The StarWeld Select

from ROFIN Laser Micro

can be operated as an

ergonomically

optimized manual

welding laser, as a

deposit welding laser

with joystick and as a

high-precision CNC

system. All process

steps are controlled via

a multifunctional joystick and a large

multicolour touch-screen display enabling

semi-automatic laser welding, CNC teach-in or

jogging of heavy workpieces.

The system can cope with workpieces

weighing up to 50 kg, which it can position with

an accuracy of 10 µm.

ROFIN adds that the TrackMode allows direct

storage of manually controlled paths and can

be used for deposit welding along curved

contours and for semi automatic operations.

The AreaFill option allows several parallel offset

welding seams to be generated for 3D surface

deposit welding.

www.rofin.com

DC current source

Optronic Laboratories

has introduced the

OL400-C controller,

which it has designed

for use with its OL

series 426 and 455

integrating sphere calibration standards.

According to the firm, the precision-constant

DC current source features microprocessor

control, a lamp-hours monitor, a wide viewing

angle two-line display, USB 2.0 interface and an

adjustable tilt handle. An optional software

development kit is also available.

www.olinet.com

488 nm laser

Coherent

The latest Sapphire

laser from Coherent is a

small-footprint OEM

source delivering

50 mW of continuous-

wave output power at

488 nm. Primarily

intended for biomedical

instrumentation such

as flow cytometry and drug discovery, the

50 mW power level will deliver increased

sensitivity leading to faster throughput and/or

higher signal-to-noise for these applications,

according to Coherent.

The Sapphire 50 mW is based on the same

optically pumped semiconductor laser

technology as its 10 and 20 mW counterparts

and also shares the same form factor, power

requirements and beam characteristics.

Coherent says that, compared with air-cooled

argon lasers, its all-solid-state Sapphire offers

the advantages of smaller size, greater electrical

efficiency, lower heat dissipation and

substantially longer lifetime.

www.coherent.com

PRODUCTS

If you would like your company’s products to be featured in this section,

please send press releases and images to James Tyrrell (james.tyrrell@iop.org).

OLE • October 2006 • optics.org/ole

Pulsed Tunable

Dye Laser

quantel@quantel.fr - +33 1 69 29 17 00 / sales@bigskylaser.com-(406) 586 0131

Quantel & Big Sky Laser

Quantel’s TDL90 offers researchers an extremely versatile

nanosecond tunable laser source.

• 200nm to 4.5

m tuning using wavelength extension options

• High Efficiency

• Compact Design

• User-Friendly

• Low ASE Oscillator Design

Quantel provides you with a complete Nd:YAG pump / dye

laser system, for an optimal mechanical stability.

Contact Quantel, Big Sky Laser or your local representative

for more details.

OLEOct06PRODUCTSp37-49 25/9/06 16:09 Page 37

Pulsed UV laser

Newport

The Explorer Scientific

from Newport is a low-

power, intracavity,

frequency-tripled and

actively Q-switched

diode-pumped solid-

state laser that delivers pulse energies of up to

120 µJ at 349 nm. The source is said to be an

ideal research tool for applications requiring

high pulse energies and peak powers at low

kilohertz repetition rates.

The Explorer can be operated from single shot

up to a 5 kHz pulse repetition rate at variable

pulse energies. Pulse widths are typically less than

5 ns and, with a pulse-to-pulse stability of less

than 3% rms, the company says that applications

will benefit from an extremely low signal-to-noise

ratio. A LabView-based GUI allows customers to

interface with the laser via a USB port.

www.newport.com

Chromatic confocal sensors

Armstrong Optical

The latest line of

confocal chromatic

optical pens

manufactured by STIL of France is now available

through Armstrong Optical of the UK. Typical

applications are listed as profilometry,

microtopography, roughness, autofocus

vibrometry, in-line inspection quality control and

thickness measurements.

A modular design allows up to 30 different

configurations for specific depth-of-field, spot

size, working distance, object slope and

photometric efficiency. Five magnifiers with focal

lengths ranging from 3.3 to 29.0 mm and six

chromatic lenses with depths of fields from

130 µm to 27 mm are available. The pens are

said to achieve a maximum axial resolution of

5 nm, an accuracy of 20 nm and a maximum

slope of 87° for diffusive objects.

www.armstrongoptical.co.uk

Fibre-coupled diode laser

Point Source

Point Source has

launched a higher-

power version of its

iFLEX2000 fibre-

coupled laser. The

latest addition delivers

30 mW at 405 nm in a

TEM00 Gaussian beam.

Laser beam

conditioning is

performed using a

singlemode fibre, which

acts as a spatial filter while also providing a

flexible beam-delivery mechanism.

The company also claims that the laser is

unique in employing forward, closed-loop power

control that is immune to optical feedback, which

in turn provides a long-term ultra-stable output

and low short-term amplitude noise. Target

biomedical applications include flow cytometry

and fluorescence imaging, although the laser is

said to be ideal for optical media applications

where spot size and resolution are critical.

www.point-source.com

Laser barriers

LaserVision

LaserVision says that its

new Laserbarrier

product is a modular

system that meets the

changing needs and

requirements of laser

users. Based on a

patent-pending material

system, the barrier

offers protection from CO2and Nd:YAG lasers up

to a power density of 10 MW/cm2. LaserVision

says that this equates to protection levels of AL4

at 10600 nm and AL6 at 1064 nm at 100 s of

direct illumination.

The barrier has a specially designed surface,

which is said to make it suitable for applications

in industry, research and even cleanroom and

medical environments. LaserVision adds that the

product can contain different or full segmented

protection modules such as cabin windows.

www.lvg.com

Fizeau interferometer

4D Technology

4D Technology, US,

has introduced the

FizCam 2000. “This is

the first-of-its-kind ‘on-

axis’ vibration Fizeau

featuring a short

coherence length source that enables

measurement of transparent samples and

assemblies that are difficult or impossible to

measure with traditional laser

interferometers,” said James Millerd, 4D’s

chief technical officer.

According to 4D, the short coherence feature

eliminates the need for extraneous coatings to

control interfering fringes by isolating and

measuring only the desired surface. In addition

to measuring parallel optical grade surfaces, the

FizCam 2000 is said to be well suited to

separating and measuring surfaces within an

optical assembly, making remote cavity

measurements, testing index homogeneity,

measuring thin optics and environmental

chamber testing.

www.4DTechnology.com

PRODUCTS

38 OLE • October 2006 • optics.org/ole

OLEOct06PRODUCTSp37-49 25/9/06 16:10 Page 38

NASDAQ: STKR

StockerYale Inc.

Tel: +353-21-4320750

Fax: +353-21-4327451

saleseurope@stockeryale.com

www.stockeryale.com

•220,000 lux @ 630 nm

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configurations

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500 mm line lengths

Applications include:

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FPD, foil, paper, plastics,

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LINESCAN ILLUMINATOR

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OLEOctAdverts39 22/9/06 13:35 Page 1

Fusion splicer

Sumitomo Electric Industries

The T-39 single fibre

core aligning fusion

splicer from Sumitomo

Electric Industries has

been designed under

the company’s ECO-

21/2 programme,

which considers the environmental effects of a

product over its lifetime. As such, the company

says that this is the first in a new generation of

splicers that comply with the European Union’s

RoHS regulations.

Sumitomo says that the T-39 has dual

independent heat-shrink ovens that improve

splice throughput and productivity. The device

also features “hands-free” operation, thanks to

the automatic starting of the splice and heat-

shrink processes.

www.sumielectric.com

Polarization-maintaining fibre

Liekki

Liekki of Finland has added a highly doped,

large-mode-area fibre with a very high cladding

absorption (Yb1200-20/125DC-PM) to its

ytterbium-doped fibre product family. Typical

applications are listed as materials processing

(cutting, marking and drilling), laser ranging,

remote chemical detection and nonlinear

frequency conversion.

The fibre has a highly doped 20 µm diameter

core and a large core-to-cladding ratio. These

features result in a nominal cladding pump

absorption of 7.1 dB/m at 920 nm, rising to

around 30 dB/m for absorption at 976 nm.

According to Liekki, this enables very short

active fibre lengths – less than 1 m for

976 nm pumping.

www.liekki.com

Gigabit Ethernet camera

JAI PULNiX

JAI PULNiX has added a

new member to its line

of gigabit Ethernet

cameras. The

TM-1327GE is a

compact progressive scan CCD camera featuring

a 2

/3inch image sensor and a frame rate of 30 fps

at the full resolution of 1392 ×1040 pixels.

Contained in a 50.8 ×50.8 ×84.8 mm

housing, the camera is said to have a wide

dynamic range with sensitivity in both the visible-

and near-infrared. Its interline transfer CCD

permits full vertical and horizontal resolution with

shutter speeds of up to 1/21 000 s.

Asynchronous reset combined with a no-delay

pulse-width-controlled shutter provides flexible

triggering and the exposure control necessary for

machine vision applications.

www.jaipulnix.com

PRODUCTS

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OLE • October 2006 • optics.org/ole

OLEOct06PRODUCTSp37-49 25/9/06 16:11 Page 40

PYSER-SGI

200LP /MM

New Calibration and

Resolution Standards For

Optical and Vision Systems

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USAF resolution chart down to

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OLEOctAdverts41 22/9/06 13:50 Page 1

561 nm DPSS laser

Laser Lines

Laser Lines of the UK is

now distributing the

561 nm Jive 75 laser

from Cobolt. Emitting

75 mW, the Jive 75 is

said to offer low noise,

excellent beam quality, long lifetime and single

longitudinal mode operation, all in a compact

package. The beam size and divergence match

those of an air-cooled ion or HeNe laser, which

is said to make the Jive a direct drop-in

replacement in flow-cytometry and microscopy

applications. A narrow spectral bandwidth and

long coherence length also make the source

useful for applications such as spectroscopy,

holography and interferometry.

www.laserlines.co.uk

SLEDs

Exalos

Exalos of Switzerland

says that its 750 nm

line of superluminescent

light-emitting diodes is

especially suited to

optical coherence tomography (OCT) and

biomedical applications. The firm claims that

its devices, which combine the spatial

coherence of a laser diode with the temporal

incoherence of an LED, provide high

suppression of second coherence peaks.

Typical values for the EXS7505-1411 are 3 mW

optical output power in a singlemode fibre and

21 nm 3 dB spectral bandwidth.

The EXS7510-1411 is said to achieve 5 mW

optical output power in a singlemode fibre and

14 nm 3 dB spectral bandwidth. Featuring a

built-in thermoelectric cooler and monitor diode,

the standard product is delivered in a 14 PIN DIL

housing. Uncooled devices in TOSA housings are

also available. The firm also offers devices at

850 and 1300 nm, which may be of interest to

developers of biomedical and OCT apparatus.

www.exalos.com

VCSELs

Vertilas

German VCSEL expert Vertilas says that its latest

generation of 1310 and 1550 nm sources

enables applications up to 10 Gbit/s, thanks to

a benzocyclobutene-based optimized device

structure. It says that this high performance

coupled with a low threshold current makes the

components valuable for the newest generation

of small-form-factor optical modules, such as

SFP+ and XFP.

The lasers are offered in standard TO-46

packages and are being integrated into

application-specific assemblies, such as pigtails

and receptacles.

www.vertilas.com

PRODUCTS

Picosecond

Diode Lasers

EPL 375

EPL 405

EPL 445

EPL 473EPL 635

10 Pre-set Repetition rates:

20 kHz - 20 MHz

Pulsewidths*down to 75ps

with optimised pulse characteristics

at each repetition rate.

Spectrally Purified Output

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Design, No External Controller

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Spectroscopy

Optimised Beam Collimation

Applications include:

•Time Correlated Single Photon

Counting (TCSPC)

•Fluorescence Lifetime Imaging (FLIM)

•Fluorescence Resonance Energy

Transfer (FRET)

•Optical Tomography of Biological

Samples

www.edinst.com

For more information contact us at:

sales@edinst.com

Edinburgh Instruments Ltd

2 Bain Square, Livingston

EH54 7DQ, UK

Tel: +44 (0)1506 425300

Fax: +44 (0)1506 425320

*Typical value may vary with model.

Bertha-von-Suttner-Str. 5 · D - 37085 Goettingen

tel. + 49 (0) 5 51 - 79 76 70 · info@metrolux.de

optical metrology

Laser Beam

Diagnostics

For Pulsed & CW Lasers

BeamLux II Software

Multiple Camera

Support

Beam Analysis in

Compliance with ISO

High Data Processing

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Cameras for

Beam Proﬁling

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XUV-VUV-VIS-IR

Highest Resolution

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Wide Range of

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Implementation

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application.

42 OLE • October 2006 • optics.org/ole

OLEOct06PRODUCTSp37-49 25/9/06 16:11 Page 42

LEDs

Osram Opto Semiconductors

Osram Opto

Semiconductors says

that its new advanced

power TopLED devices

are 50% brighter than

their predecessors,

thanks to thin-film

technology. The company quotes an output of

19 lm for green and amber, 15 lm for white and

red, 14 lm for yellow and 5 lm for blue, all at

140 mA. Osram says that this new range is

positioned between standard and high-power

LEDs and is ideal for area and effect lighting. An

SMT package ensures that the LEDs are

compatible with standard solder processes.

www.osram-os.com

Microinspection system

Moritex

Moritex of the UK says

that its MS804

Scopeman is a powerful

and easy-to-use

microinspection system

that is able to

undertake almost any

real-time industrial

inspection or quality-assurance task. The system

is available with a range of zoom lenses

(16–200×); x, y and z stages; camera mounts

and a variety of imaging peripherals.

The company says that a combination of

multi-exposure, high-intensity LED lighting and

intuitive software for fast and simple acquisition

allows the system to deliver high-resolution,

1280 ×960 pixel images. It adds that, by

changing the camera’s shutter speed and

combining “bright” and “dark” images, the

MS804 provides an enlarged dynamic range.

www.moritex.com

Photon-counting training

SensL

SensL of Ireland has launched two

complementary training courses for academics,

researchers and engineers who wish to learn

more about the technology and techniques used

in photon detection. The products are called

PCEdu-1: photon counting fundamentals and

PCEdu-1T: photon timing upgrade.

PCEdu-1 is an entry level lecture and

laboratory series that SensL says is ideal for

academics looking to start a low-light sensing or

semiconductor device physics training module.

It is also said to be ideal for OEMs looking to

bring an R&D team up to speed quickly.

PCEdu-1T is an upgrade package that takes

the training to a higher level through a series of

lectures and lab experiments dealing with real

photon-counting scenarios.

www.sensl.com

PRODUCTS

1 Bay Street

Stirling, NJ 07980

Telephone: 908-647-6601

Fax: 908-647-8464

info@fiberguide.com

THE PHOTONICS PACKAGING COMPANY

fiberguide

industries

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Eduraguide HOPC™ Fibers

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Apowerful laser delivery system in a

surgeon’s skilled hand helps cure people.

These medical laser systems are made

possible by utilizing Fiberguide Industries

new Eduraguide HOPC™ fibers.

The Eduraguide HOPC™ line of large

core multi-mode fibers have a numerical

aperture of 0.39 and employ a Hard Optical

Polymer Coating (HOPC™). With increased

beam intensity, this exceptional coating

offers superior fiber strength and reduces

static fatigue in humid environments.

Eduraguide HOPC™ fibers offer excellent

connection alignment and they have a high

core to clad ratio. Eduraguide HOPC™ is

also made available in silica/silica HOPC™

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The finest medical laser delivery system

starts with Eduraguide HOPC™ fibers.

Call Fiberguide Industries to discuss your

specific requirements.

www.photonlines.com

Streak Camera

UV-LED module

High speed Camera

44 OLE • October 2006 • optics.org/ole

OLEOct06PRODUCTSp37-49 25/9/06 16:12 Page 44

Colour CCD camera

Toshiba

The IK-TF9C from

Toshiba’s Imaging

Systems Division is a

three-chip, colour CCD

camera with a resolution

of 2048 ×1536 pixels.

Also incorporating Toshiba’s progressive scan

technology to eliminate image jitter, the camera

is said to be ideal for high-speed industrial

machine vision applications.

Measuring 44 ×44 ×78.3 mm and weighing

165 g, the camera has a frame rate of 20 fps

(full frame) and 40 fps (partial scan). Other

specifications include a C-mount for lenses, an

8-bit RGB digital output and CameraLink

compatibility for ease of operation.

www.cameras.toshiba.com

Software-development kit

Prosilica

Industrial CCD camera

maker Prosilica has

released Linux and QNX

software-development

kits (SDKs) for its range

of GigE Vision cameras,

complementing the

company’s existing Microsoft Windows SDK.

According to Prosilica, the GigE Vision SDKs

provide programmers with the means to control

and capture images from its gigabit Ethernet

cameras. In addition the Linux SDK works on

both Intel ×86 and PowerPC hardware. The SDK

also includes sample code to help

programmers to use Prosilica’s cameras in their

Linux-based applications.

www.prosilica.com

Deep-cooled CCD

Princeton Instruments/Acton

Princeton Instruments/Acton has added the

2048 series of front- and back-illuminated

cameras to its PIXIS line of CCD cameras. Based

on e2v technologies’ 42-40-2048 ×2048

format sensor with an imaging area of

26.7 ×26.7 mm, PI/Acton says that the

PIXIS:2048 offers deep cooling better than

–70 °C (via a thermoelectric Peltier) with a

vacuum guaranteed for the life of the camera.

The new cameras come with the familiar

traits of the PIXIS line, such as dual

100 kHz/2 MHz digitizers, ultra-low read noise

of 3e–rms read noise (at 100 kHz), all-metal

hermetic seals, USB 2.0 interface and single

optical window design.

Other specifications include flexible binning,

ROI capabilities and WinView software. The

company adds that a toolkit with LabView

examples and its own PVCAM library of function

calls is available.

www.piacton.com

Raman workstation

McPherson

The McPherson Raman

workstation is available

for the popular laser

lines between 325 and

830 nm. Systems

include a solid-state

laser, speciality filters and a sample chamber

with laser focusing and signal-collection optics.

Sample chambers compatible with cryogenic

sample holders are also available for

photoluminescence work.

All elements in the workstation are mounted,

aligned and integrated with a research grade

350 nm, f4.8 spectrometer with CCD and

software. The user-friendly single-stage

instrument is said to ensure good signal to noise

and ease of use for detecting Raman-shifted

emission above 300 wavenumbers.

www.mcphersoninc.com

Imaging spectrometer

HORIBA Jobin Yvon

HORIBA Jobin Yvon has

released the iHR550

imaging spectrometer.

With a focal length of

0.55 m, the device

offers the ability to perform multitrack

experiments with up to 20 fibre inputs. Incorrect

and rediffracted spectra are eliminated using an

asymmetric Czerny–Turner design in conjunction

with an on-axis grating drive system.

The iHR550 has two entrance and two exit

ports. Each exit port can be configured for use

with either an array detector, such as a CCD, or

a slit for use with a PMT. The company can

supply the iHR550 in a variety of configurations

for all spectroscopic measurements, including

Raman, photoluminescence, emission and

imaging or multitrack spectroscopy.

www.jobinyvon.co.uk

Dual-wavelength laser diode

Rohm

The RLD2WMUV2 from

Rohm is a singlemode,

dual-wavelength laser

diode that emits at

both 785 and 655 nm,

making it an ideal source for both DVD-ROM

and DVD players. The firm says that

optimization of a strained quantum well has

allowed a reduction in threshold current and

good temperature characteristics.

Rohm quotes a threshold current of 18 mA for

785 nm and 20 mA at 655 nm, both at 25 °C.

The emission pointing distance is specified at

110 µm. The device can be combined with

Rohm’s high-frequency modulation IC

(BU9369FVM) for reduced noise.

www.rohmelectronics.com

PRODUCTS

OLE • October 2006 • optics.org/ole

OLEOct06PRODUCTSp37-49 25/9/06 16:12 Page 45

Untitled-3 8/25/06, 1:39 PM1

Beam profiler

Photon Inc

Photon Inc has

released a 12-bit beam

profiler with FireWire

(IEEE 1394)

connectivity and a

large dynamic range.

Available in two

versions, model 2523 features a 2

/3inch

format (9.0 ×6.7 mm) CCD with 6.45 µm

pixels, whereas model 2512 is based on a 1/2

inch format (6.5 ×4.8 mm) CCD with 8.3 µm

pixels. Both profilers have a small form factor

(49 ×62 ×62 mm), making them easy to insert

into optical paths. According to the firm, the

beam profiling system does not require a

frame-grabber card so can be moved easily

between different computers.

The device measures both continuous-wave

and pulsed beams over the 190–1100 nm

wavelength range. The firm claims that by using

extended range imaging, the unit can obtain

profiles with a dynamic range as high as 144 dB

(24 bits of digitization). The company adds that

very large dynamic range is important in many

applications, especially lens characterization,

where lens aberrations are apparent from faint

features around a strong central peak in the

beam profile.

www.photon-inc.com

785 nm laser

B&WTek

B&WTek has introduced its Cleanlaze high-

resolution and wavelength-stabilized laser

technology for Raman spectroscopy. Emitting at

785 nm, multimode models offer 0.2 nm FWHM

while singlemode versions feature a typical

linewidth of 0.02 nm. Output power options

range from 25 mW to more than 1 W at 785 nm.

Sources emitting at 980 nm and other

custom wavelengths are available. The lasers

are said to be ideal for OEM Raman

instrumentation, process, portable and lab

applications, thanks to their light weight, small

footprint, high stability, narrow linewidth and

low maintenance cost.

www.bwtek.com

Waveguide optics simulation

Optiwave Systems

Optiwave Systems has

released OptiBPM8 –

the latest version of its

waveguide optics

design suite. This has

advanced LP and

vector-mode solvers for circular fibres. Optiwave

says that these meshless fibre-mode solvers find

modes using a transfer matrix method in

cylindrical co-ordinates.

Other new features in OptiBPM8 include

intelligent optimization engines, the ability to

import DXF and GDSII mask file formats and a

simulation engine performance boost that the

company says allows the software to run 50%

faster than previous versions.

www.optiwave.com

High-power diode laser

LIMO

LIMO has introduced a prototype 25 W diode laser

that emits a 10 ×10 mm beam with a divergence

of 2 ×2 mrad. The company says that the laser,

called LIMO25-C10x10-DL980, has a beam-

parameter-product of 5 mm mrad and yields

power densities of 5 MW/cm2in a 25 µm spot. It

hopes to double the output power to 50 W in the

near future.

LIMO also offers a fibre-coupled version of

this source. The LIMO25-F50-DL980 delivers

25 W via a 50 µm fibre core with a numerical

aperture of 0.22.

www.limo.de

Translation stage

PI’s P-652 piezoelectric

linear-motor-driven

translation stage

consists of four parts

and, according to the

firm, can replace

classical drive

elements, such as rotary motor/leadscrew

assemblies or electromagnetic linear motors in

a microsystem. Measuring only

9.0 ×6.5 ×2.4 mm, the P-652 stage offers a

travel range of 3.2 mm and can move at

velocities of up to 80 mm/s. Other

specifications include a resolution of better than

0.1 µm, a holding force of 20 g and an operating

current of 55 mA. Highly integrated electronics

are available for 3 V control.

www.pi.ws

Encapsulant

Nusil Technology

Nusil Technology has added the GEL-9617-30

to its range of Lightspan materials for the

photonics industry. Designed as a protective

encapsulant for LED or other photonic

applications, the gel has a high refractive index

of 1.54 to maximize optical efficiency. Nusil

says that the encapsulant resists optical

degradation when exposed to ultraviolet

radiation or extreme temperatures. It adds that

the gel also serves as an effective medium for

phosphor incorporation. Formulated to cure at

room temperature, the gel can be cured rapidly

with heat to address issues of substrate and

lens delamination. The GEL-9617-30 is

available in 50 ml side-by-side kits for

evaluation purposes.

www.nusil.com

PRODUCTS

ALL FIBER

BEAM

COMBINER

A brand new singlemode fused

ﬁber beam combiner for visible

laser beams.

Blue/Red, Green/Red, Blue/Green

versions available.

www.point-source.com/ole

OLE • October 2006 • optics.org/ole

OLEOct06PRODUCTSp37-49 25/9/06 16:13 Page 47

Power supply

Power-One

The BLP30-3000G AC–DC power supply is

now available from Power-One. Measuring just

2×4 inches, the 30 W unit is quoted as

producing 5 V at 3.5 A (5 A peak), 12 V DC at

2 A and –12 V DC at 0.5 A. The supply is said

to be the ideal power source for space-

constrained, 1U-high applications, such as

data networking, medical instrumentation and

external disk storage. RoHS compliant, the

unit operates over a wide 90–264 V AC input

range and provides short-circuit and

overvoltage protection.

www.power-one.com

Shutters and machine vision

Melles Griot

Melles Griot, a provider

of photonic

components, has added

shutters and machine

vision products to its

online catalogue. The

firm’s IES series shutters include an adjustable

iris diaphragm, xsynchronization and a manual

actuation lever that allows the device to operate

without an electrical signal. The firm also

supplies UltraThin versions designed to fit into

restricted spaces. Both IES and UltraThin designs

feature spring-steel blades with a Teflon

impregnated, matte-black finish and include a

multiblade shutter mechanism that is said to

give near 100% light extinction.

According to Melles Griot, its range of four

high-performance telecentric lenses suit

machine vision, metrology and precision-

gauging applications. The firm claims that the

lenses provide low optical distortion and a high

degree of telecentricity for accurate image

reproduction, particularly when viewing 3D

objects. Lens accessories such as

teleconverters, right-angle attachments, fibre-

bundle collimators and anodized mounting

brackets are also available from the firm.

www.mellesgriot.com

16 ×2 character PLED

One Stop Displays

One Stop Displays has

released its 16 ×2

character PLED in a

new module size of

84 ×44 mm. Dubbed

OSD1602M03-F, the RoHS compatible unit

features 160˚ viewing angles, over 100:1

contrast ratios and a low 20 mA of current draw

at 40 nits of uniform brightness. The display

uses the standard Hitachi HD44780 character

LCD interface and command set, and suits

hand-held products, instrumentation and

security panels to name just a few applications.

www.onestopdisplays.net

PRODUCTS

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48 OLE • October 2006 • optics.org/ole

OLEOct06PRODUCTSp37-49 25/9/06 16:14 Page 48

Anti-reflective ball lenses

DSI

Deposition Sciences Inc

(DSI) is offering

antireflection (AR)

coated ball lenses in a

variety of glass indices

and in new larger sizes up to 10 mm diameter.

Highly durable and scratch resistant, the firm’s

IsoSphere range of AR coated lenses is

available with transmission values > 99.5% in

indices of up to nd2.0 at 550 nm. DSI claims

that its ball lenses are an affordable and

mechanically compact way of collimating the

output of an optical fibre or laser diode. Lenses

are resistant to most chemicals and are said to

suit aerospace, oil-field exploration, oil refining,

marine and undersea applications.

www.depsci.com

Off-the-shelf aspheres

Asphericon

Asphericon of Germany has launched a range of

“off the shelf” aspheres. Dubbed Standard

Precision Apsheres (SPAs), the lenses are

available in a number of diameters from 6 to

100 mm and are made primarily from high-index

material with low dispersion. The lenses are

manufactured by CNC grinding and polishing

and can be supplied with a choice of three

standard coatings. According to the firm, all

SPAs are available directly from stock.

www.asphericon.com

UV radiometer

Dymax

Dymax has added the

ACCU-CAL 50

radiometer to its range

of technical adhesives

and ultraviolet (UV)

curing systems. The unit

allows users to monitor

the intensity of a UV

curing source and assess adhesion

performance. Compatible with all types of

DYMAX UV curing systems, such as spot lamps,

flood lamps and conveyors, the device is said to

be simple to operate. It offers repeatable

measurement in the UVA spectrum

(320–395 nm) from 1 mW/cm2to 40 W/cm2.

www.dymax.com

PRODUCTS

Single-mode, single-frequency,

tunable diode lasers for

industrial applications

·· Spectral range 760 .. 2300 nm

··Narrow linewidth (1 .. 4 MHz)

··Up to 1400 GHz

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(e.g. 58 x 44 x 30 mm3)

·· Full computer control

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··Gas sensing

·· Combustion monitoring

·· Drug screening

·· Interferometry

·· Tunable THz generation

OEM applications are encouraged

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Tune it to Your

Wavelength

OLE • October 2006 • optics.org/ole

B&W Tek www.bwtek.com 39

BFI Optilas www.bfioptilas.com 21

Breault Research Organization

www.breault.com IFC, 8

Cambridge Technology

www.cambridgetechnology.com 25

Crystal Systems www.crystalsystems.com 18

CVI Technical Optics www.cvilaser.com OBC

Duma Optronics www.duma.co.il 35

Edinburgh Instruments www.edinst.com 42

Edmund Optics www.edmundoptics.co.uk 32

EKSPLA www.ekspla.com 38

ELCAN Optical Technologies

www.ELCAN.com/create 4

Electron Tubes www.electrontubes.com 41

Electro-Optical Products www.EOPC.com 32

Esco Products www.escoproducts.com 28

Evatec Process Systems www.evatecnet.com 28

Femto Messtechnik www.femto.de 40

Fiberguide Industries www.fiberguide.com 44

Fuji Magnetics www.polymer-optics.com 15

GPD Optoelectronics www.gpd-ir.com 28

GWU Lasertechnik www.gwu-group.de 24

HC Photonics www.hcphotonics.com 39

High Q Laser www.highqlaser.com 40

Hilger Crystals www.hilger-crystals.co.uk 36

Holo Or www.holoor.co.il 32

IPOT 2007 www.ipot.co.uk 36

Jenoptik Polymer Systems www.jenoptik-ps.de 15

Kentek Corporation www.kentek.com 9

Laser 2007 www.world-of-photonics.net 31

Laser Components (UK) Ltd

www.lasercomponents.co.uk 7

Lasermet www.lasermet.com 39

Laser Quantum www.laserquantum.com 35

Leister Process Technologies www.axetris.com 34

Melles Griot www.mellesgriot.com 13

Metrolux Optische www.metrolux.de 42

Möller-Wedel Optical

www.moeller-wedel-optical.com 18

Multiwave Photonics

www.multiwavephotonics.com 41

New Focus www.newfocus.com 22

Newport Spectra-Physics www.newport.com 48

Ophir Optronics

www.ophiropt.com 6, 14, 50, IBC

Optikos www.optikos.com 32

Opto Taiwan 2007 www.optotaiwan.com 43

PCO AG www.pco.de 45

Photon Energy www.photon-energy.de 36

Photonex 2006 www.photonex.org 12

Photonic Products

www.photonic-products.com 28

Photonics West 2007

www.spie.org/events/pw 46

Photon Lines www.photonlines.com 44

Physik Instrumente www.pi.ws 16

Point Source www.point-source.com 47

Pyser-SGI www.pyser-sgi.com 41

Quantel www.quantel.fr 37

Quintessence Photonics

www.QPClasers.com 10

Scitec Instruments www.scitec.uk.com 32

Spanoptic www.spanoptic.com 48

Stanford Research Systems

www.thinkSRS.com 20

StockerYale Inc www.stockeryale.com 15, 39

Tempo Plastic www.tempo-foam.com 18

Toptica www.toptica.com 49

XeniCs www.xenics.com 30

ADVERTISERS’ INDEX

The index is provided as a service and, while every effort is made to ensure its accuracy, Optics & Laser

Europe accepts no liability for error.

OLEOct06PRODUCTSp37-49 25/9/06 16:14 Page 49

PEOPLE

To advertise your job vacancies, contact Cadi Jones (tel: +44 (0)117 930 1090; e-mail: cadi.jones@iop.org).

50 OLE • October 2006 • optics.org/ole

SUDOKU PUZZLE

We hope you enjoyed September’s Sudoku

puzzle. You can check your answers against last

month’s solution on the left.

If you are new to Sudoku, this is how it works:

each puzzle consists of a 9 ×9 grid that is

subdivided into 9 smaller grids of 3 ×3 squares.

To complete the puzzle, you must ensure that

each row, column and 3 ×3 square contains the

numbers 1–9. All it takes is logic so try not to

guess at the numbers.

GERMANY

Gretschel takes director

role at QioptiQ GmbH

Ingo Gretschel has

been named as the

managing director at

QioptiQ GmbH,

which is based in

Asslar, Germany.

Formerly head of

optoelectronic sales at German firm Docter

Optics, Gretschel has many years’ experience

in optomechanical design and in the

manufacture of products and components

for both military and commercial

applications. Gretschel took up his new role

on 1 August and reports to QioptiQ group

chief executive officer Benoit Bazire.

FINLAND

Orsila continues as the

chairman at Modulight

Modulight has announced that Seppo Orsila

has been re-elected to the position of

chairman of the board but has withdrawn

from his operational role as chief financial

officer and vice-president of marketing at the

Finnish firm. A founder of Modulight, Orsila

will continue to contribute to the strategic

planning of the firm in his role as chairman.

Modulight was founded in 2000.

Optical software expert

adds to developer team

BRO, US, has

appointed Jianhua

Jiang as a

computational

optical scientist.

Jiang joins the firm

after nearly 10 years

of optical training and research at the

University of Alabama in Huntsville (UAH),

most recently as the leader of the

simulation group at the UAH Nano and

Micro Devices Center.

The firm has also recently made additions

to its Technical Customer Service Group

through the appointment of William

Donnelly as senior optical engineer and

Robert Shroder as optical engineer.

FRANCE/US

Liebowitz to lead Teem

Photonics in the US

Teem Photonics of

France, a specialist

in passively

Q-switched

microlasers and ion-

exchange integrated

optics, has appointed

Jay Liebowitz as president of its wholly

owned US subsidiary. Liebowitz had

previously been executive vice-president.

“Jay has helped to diversify our business

from telecoms and towards a wider breadth

of industries, including biophotonics,

instrumentation, remote sensing and

materials processing,” said Antoine

Kevorkian, chief executive officer of Teem

Photonics SA. “We see a significant growth

opportunity for our Q-switched microlaser

business in North America, so it makes

sense to elevate Jay’s position for leading

our expansion in this continent.”

Albe steps into a crucial

sales role at BinOptics

US-based BinOptics, a

maker of integrated

microphotonic

components for

optical

communications

and data-storage

applications, has named Edward Albe as vice-

president (VP) of sales and marketing. Most

recently, as VP of sales and customer service

at Picolight, Albe led the firm’s resurgence in

the fibre-optic transceiver market-place.

Founded in 2000, BinOptics is

headquartered in Ithaca, New York.

PVS 50 P 33(LP) HA Old 02 143

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