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As Photonics West winds up for another year, Jacqueline and I are heading to the airport for the night flight to London. As ever, it's been a blast: we've been impressed by the sheer size of the show, and by the truly innovative products that have been on display at many of the booths.

You can read all about our highlights of the show in the blog entries below. So it's goodbye for now, and see you all again next year.

The number of new products and innovations on the show floor this year is impressive. Today, I stopped by Imagine Optic's booth (booth 715) and was treated to a demonstration of its new SL-Sys neo system, which uses the company's wavefront sensor technology.

The interesting thing about this fully-automated system is that it can completely characterize a lens at the push of a button - and it's ideal for studying the lenses used in digital cameras or mobile phones.

"This is the only commercially available system that can completely characterize optical components 1 to 12 mm in diameter of any numerical aperture," company director Samuel Bucourt explained. "The new innovation is the way that we illuminate the sample. We can measure the optical element's aberrations as wavefront errors over the entire field of view and/or at any point therein."

The control software that runs the SL-Sys neo lets the user decide what parameters they want to investigate. The user simply loads the lens into the instrument and clicks the boxes on the front panel of the software to evaluate quantities such as the 3D and through-focus MTF, chromatism, distortion and vignetting. It takes about 20 seconds to complete the measurement process.

"The SL-Sys neo is ideal for industrial R&D programmes and for production line quality control," said Bucourt. "It is now commercially available and has a lot of good functionality that has not been easy to realize in one product."

This morning's executive panel focused on the realities of doing business in China. Adonis Mak of Laser Focus World China, which is published out of Hong Kong, highlighted the opportunity for companies in the West to supply laser products to scientific research institutes in China.

"All colleges in China have physics and optics departments," he said, "and in many cases they have abundant budgets to buy high-end devices and equipment."

Within the industrial sector, Mak identified four key markets in China that rely on laser technology: consumer electronics, car production, semiconductor manufacture, and optical communications. Car manufacturing and to some extent semiconductor fabrication have benefited from inward investment from leading overseas firms, while China is now the largest manufacturer of consumer electronics in the world.

Laser manufacturers have not been slow to recognize this opportunity. Newport-Spectra Physics established a presence in China 25 years ago, while Coherent has been in the country for the past decade. More recent arrivals have been big hitters such as Edmund Optics, IPG Photonics, Dilas and Ocean Optics.

But Mak acknowledged that many challenges remain for Western firms. "Guan-zi [relationships] still play an important role when doing business in China, which means that you need a local partner," he said. "Most research institutes are also controlled by the government, and that can make buying behaviours difficult to predict."

Robert Huang of Wavelength Technology (booth 6247), a company based in Singapore that established a Chinese facility in 2003, highlighted the problems associated with IP piracy. When asked how companies should protect their intellectual property, he said: "You've got to be fast so that no-one has a chance to copy you."

But Huang said that photonics firms should not be scared to invest in China. "The technology and quality of Western suppliers is welcome in China, but price is also a key issue."

We've heard a lot this week about photovoltaics, and in particular about the role that lasers have to play in their fabrication. At the Lasers and Photonics Marketplace Seminar on Monday, Newport's Dave Clark explained how laser scribing is an essential technology for the manufacture of emerging thin-film solar cells, while a visit to the Coherent booth on Tuesday revealed that this company also sees big potential in the photovoltaic market.

So it was interesting when yesterday's executive panel debated whether photovoltaics offer a real opportunity for laser manufacturers, or whether it's all just a chimera. Moderator Steve Eglash pointed out that the solar market is currently worth $15 bn worldwide, and that the solar sector has already seen a number of successful IPOs. He himself has "voted with his feet", being CEO of solar start-up Cyrium Technologies.

Others were more cautious. Newport's director for strategic marketing, Randy Hyler, clearly sees an opportunity for laser makers, but believes it will be a long-term play. Certainly, lasers aren't crucial for the manufacture of silicon solar cells, which continue the dominate the market, which means that companies such as Newport might need to wait until thin-film versions become more popular.

Hyler also pointed out that 99% of solar cell deployments have so far been in Japan and Germany, where government rebates have made the finances look more attractive. The danger, he says, is that demand will fall away once these programs have run their course.

Meanwhile, Stuart Schoenmann, CEO of CVI Melles Griot, says that he is "still evaluating" the market opportunity. Interestingly, CVI Melles Griot is based in Albuquerque, New Mexico, where Schott is currently building a solar factory.

Perhaps the most sceptical was Trumpf's Holger Schlueter, who referred to the rush for photovoltaics as a "solar craze". He also maintains that there's no point investing in renewable energy sources without stable power grids and storage.

New on the Ophir-Spiricon booth was its wireless interface for its laser measurement system that exploits Bluetooth technology - which company president Gary Wagner told me is an industry first. In a live demonstration of the Quasar system, a laser energy meter was positioned close a light source on one end of the booth, and the smart heads and computer were located at the other end. The graphical display clearly showed the 60 Hz oscillations in the mains-driven light output.

Wagner explained that the laser meter data can be broadcast to any PC or laptop within 10 m. He says that the system not only avoids the need for lots of cables, but is also particularly suitable for applications in a tight space - such as high-power lasers that are hidden behind barriers.

Quasar is compatible most Ophir smart heads, including thermopile,
photodiode and pyroelectric versions. An optional antenna can also extend
the wireless range of up to 60 m. "Combining wireless technology with laser power/energy measurements is an enabling technology," said Wagner.

When I saw Ocean Optics (booth 927) promoting "the world's coolest modular measuring suite that is like nothing you've ever seen before" on its booth, I just had to go and investigate. The product with this tag-line is the company's new "Jaz" spectrometer - and I thought it lived up to the claim.

I was amazed when Marco Snikkers, the company's commercial director for EMEA, handed me the Jaz. It's got an embedded micro-processor, an OLED display, a slot for an SD memory card and Ethernet connectivity. A lot of thought has obviously gone into the product design because it has the look and feel of a PlayStation controller and is very simple to use - its just like using a digital camera.

The idea is that you hold the Jaz up to whatever you want to measure, view the spectrum on the display and press save. The display gives you a rough idea of what the spectrum looks like and then you can view it in more detail by transferring the spectral data over to your PC.

A simple menu system lets you choose the type of measurement you want to make: reflectance, transmittance etc. The design is also modular so, as Snikkers demonstrated on the booth, the Jaz can also be expanded to include a light source, rechargeable lithium-ion battery and up to eight spectrometer modules.

As well as the Jaz, Ocean Optics is exhibiting a laser assisted microwave plasma spectroscopy (LAMPS) system, which extends the capabilities of conventional laser induced breakdown spectroscopy (LIBS).

"Current LIBS technology ablates a minute portion of the solid or liquid sample and then analyzes the resulting plasma," explained Snikkers. "LAMPS takes this a step further by employing a special microwave cavity to enhance the plasma discharage, which increases the sensitivity greatly."

Last but not least, the company is also showing a new line of spectrometers that use a back-thinned CCD sensor which has an improved UV response. The products to look out for are the Maya2000 series and the QE65000 spectrometers.

A new way to dramatically speed up the electromagnetic simulation of CMOS image sensors was being demonstrated today on the Synopsys booth. In one example cited by Ric Borges, Synopsys' technical marketing manager, the simulation time was reduced from more than 13 hours to just 22 minutes.

The key to this step-change in performance is hardware acceleration technology developed by Acceleware, a developer of high-performance computing applications. According to Ryan Schneider, the company's CTO, Acceleware's approach is to exploit the computing power of graphics processing units (GPUs) to deliver significantly more processing power in a deskside unit.

The solution developed by the two companies exploits Acceleware's ClusterInABox Quad Q30 workstation, which comprises a workstation plus two accelerator deskside units to deliver up to two Teraflops of computational power. This has been combined with Synopsys' device simulation software, known as Sentaurus, that exploits a finite-difference time-domain algorithm to model in 3D the behaviour of light within a CMOS image sensor.

According to Borges, designers of image sensors are increasingly turning to computer simulation to optimize performance before fabrication. With the move to 200 mm and 300 mm wafers, he says, a company could spend tens of thousands of dollars on a single trial run.

Normally, device engineers simulate the transmission of light through a single pixel, and then use those results to improve device performance. It's also crucial to model the behaviour of a small array of pixels to check for cross talk, but the computing overhead makes that prohibitive except as a very final check.

Now, says Borges, engineers can get the results from these larger simulations in a fraction of the time, which means that cross-talk issues can be identified much earlier in the design process. In the highly competitive optoelectronics sector, where speed-to-market is crucial, Synopys and Acceleware believe they are onto a winner.

The world's fastest CMOS-based digital camera was on show at the Vision Research booth today. The Phantom V12 can record up to one million frames per second, but Paul Laureano, director of international sales, told me not to get too hung up on this headline figure. More important is the combination of high resolution and high speed that can be achieved at around 40,000-50,000 frames per second.

At the heart of the camera is a 1280x800 high-definition CMOS sensor that has been optimized for high-speed imaging applications. The resolution that can be achieved depends on the frame rate: at full resolution the camera can record 6315 frames per second, while at the maximum speed the resolution falls to 256x8.

The light sensitivity of the camera has been optimized by combining an active pixel size of 20 µm with improved quantum well efficiency, while a shutter speed of down to 300 ns eliminates blur and accentuates detail.

According to Laureano, Vision Research was the first company to introduce CMOS image sensors into high-speed cameras, and the Phantom V12 is the result of the company's engineering expertise in this area. The camera is designed for recording extraordinarily fast events, specifically ballistics and explosions testing, and those that take place at the microscopic level.

With many firms touting their fibre laser technology and others talking up the power of their diodes, it was something a bit different for me today to meet Keming Du. He's the general manager of German firm EdgeWave (booth 1801) who are pioneering the development of slab lasers.

First a bit of background. Du had been working on slab laser technology at the Fraunhofer Institute for Laser Technology in Aachen, decided to spin out a company in 2001 to commercialise the idea and EdgeWave was born.

EdgeWave's key product is a diode-pumped solid-state laser based on a slab design: the INNOSLAB laser. Through a combination of crystal shape, cooling and resonator design, Du explained that INNOSLAB lasers have many unique qualities.

"Our lasers have a short pulse duration and high peak output power," he told me. "They also have high beam quality - and we have the ability to change the beam profile from a line, square or circular shaped Gaussian or a top-hat."

The company's latest product is the INNOSLAB HD-series, a 600W average power electro-optically Q-switched laser with a line or square top-hat beam profile. Du reckons that a 2D line beam profile with a top-hat profile in both dimensions could be useful for solar cell applications as the intensity of the beam does not drop off in a Gaussian fashion.

Other products produced by EdgeWave are diode-pumped, electro-optically Q-switched Nd:YLF, Nd:YAG and Nd:YVO4 lasers capable of second, third and fourth harmonic generation. "Beam quality is M2 less that 2 for all our products, pulse energy up to 60 mJ, pulse length down to 4 nanoseconds and pulse repetition rate up to 150 kHz," said Du.

This morning we learned from Eugene Arthurs, SPIE's executive director, that Photonics West will be held in San Francisco's Moscone Center in 2010. The reason is clear: the San Jose Convention Center is no longer able to cater for the growing number of exhibitors and delegates who visit the show every year.

Indeed, for the first time this year the show organizers could not accommodate all the exhibitors in the Main Hall and the South Hall, itself a semi-permanent extension to the main convention center. An extra tent has had to be added onto one end of the South Hall, which is reported to leak when it rains.

Arthurs says that plans had been in the pipeline to extend the McEnery Convention Center, but the city had been unable to afford the work in the wake of the telecoms downturn. As a result, SPIE has taken the decision to host the event in the larger facility in San Francisco.

But, he says, don't make the mistake of booking your tickets to San Francisco next year. Photonics West 2009 will be back at the San Jose Convention Center just one more time.

"This is a completely new class of materials that could really change the field of optoelectronics," asserted Fred Schubert of the Rensselaer Polytechnic Institute (RPI), speaking at one of the technical sessions this afternoon. He was referring to the emergence of low refractive index materials that he believes can deliver big improvements in the efficiency of optoelectronic devices such as LEDs and solar cells.

So what is a low refractive index material? Schubert points out that no natural solid materials have a refractive index lower than about 1.4 - silica comes in 1.46, while the more exotic magnesium fluoride has a refractive index of 1.39. And yet the performance of many optical components depend on changes in refractive index, and increasing the difference in refractive index improves some of the most important figures of merit.

Schubert and colleagues at the RPI have now demonstrated that materials with a refractive index of down to 1.05 can be fabricated using a process called oblique-angle evaporation. This process has been shown to produce a self-organized array of nanorods, with the pores between individual nanorods measuring 2-8 nm - much smaller than the wavelength of light. As a result, the surface morphology of the nanorod layer is completely smooth and featureless.

What's more, the refractive index of the nanorod thin film can be controlled by altering the angle at which the rods are deposited. Larger angles produce a more porous structure, which in turn has a lower refractive index, while smaller angles result in denser layers that have a higher refractive index.

This tunability has been exploited by Schubert's team to fabricate graded refractive-index layers that act as almost perfect antireflective coatings. He explained that reflectivity depends on the change in refractive index between two materials, which means that reflections can be minimized by changing the refractive index in a series of small steps.

Results presented by Schubert show that graded coatings can reduce reflectivity to less than 0.5% over a wavelength range of 570-1000 nm. And incorporating these antireflective layers into LEDs - which are typically made from semiconductors with high refractive indices - has also been shown to increase light output by more than 40%. And Schubert believes that low refractive index material could also improve the performance of optical sensors, solar cells and other optical components.

Optically-pumped semiconductor laser technology turned out to be a theme for my day. After visiting Coherent, I went along to a presentation given by Ulrich Steegmueller of Osram Opto Semiconductors entitled: "Green laser modules to fit laser projection out of your pocket". This talk was essentially covering mobile display applications such as cell phones, pico-projectors and heads-up displays.

According to Steegmueller, such systems require red, green and blue intensity modulated lasers offering between 30 and 50 mW per colour. The blue source, for example, could be an InGaN laser diode emitting at 440 nm while the red source could be an InGaAlP diode operating at 640 nm. Needless to say, it is the green emitter that is causing all the headaches as there is no suitable direct emitting laser diode available.

The solution that Osram has been pursuing is a frequency doubling scheme involving an optically-pumped semiconductor (OPS) chip at 1060 nm. A standard 808 nm diode pumps the OPS chip and then a PPLN crystal is responsible for the doubling. Using a tiny cavity length and a thin doubling crystal, Osram has managed to produce a green source in a package measuring just 13x6.8x4.8 mm.

"The latest concept targets green output powers of to 50mW at wallplug efficiencies greater than 5%, limiting total electrical power consumption to less than 1W," said Stegmueller. "We also use micro-optics to minimize the package volume. The lasers operate in TEM00 mode and direct amplitude modulation at up to greater than 30 MHz offers easy integration into scanning projector engines."

Although there is more work to be done on the performance, Stegmueller concluded by saying that green lasers are getting small and powerful enough to enable tiny projectors.

Coherent (booth 1517) was keen to show-off its optically-pumped semiconductor laser (OPSL) technology. The new Mantis - a cost-effective oscillator for short pulse (broadband) ultrafast applications - incorporates a 5 W green pump laser based on monolithic OPSL technology rather than a traditional DPSS pump. A major application for the Mantis is seeding short pulse amplifier/OPA systems to generate tunable high energy, sub-35 fs pulses.

Next up was the OPSL-577-3 which, as the name suggests, delivers 3W of yellow output at 577nm. It turns out that this wavelength is exactly matched to the main absorption peak of oxygenated haemoglobin so could be used for laser photocoagulation treatment of wet-form macular degeneration.

Other OPSL lasers on display were being targeted at the entertainment and light show markets. Here, a unique feature of the OPSL design is the ability to directly modulate the output of the lasers up to 100 kHz.

A visit to the Intense booth this morning revealed that the Scottish firm's acquisition of High Power Devices (HPD) in April last year is yielding a range of new products that make best use of the two companies' core competencies.

First up is the Power Core 808, a single-emitter device that delivers up to 4 W at 808 nm. The chip exploits Intense's proprietary Quantum Well Intermixing (QWI) technology to achieve high power output, and combines a small emitting aperture (100 µm) with low beam divergence. But the device also exploits packaging technology developed at HPD to enable the chip to be supplied in a number of different enclosures.

The 808 nm device is aimed at coding and marking applications, but Intense CTO John Marsh told me that this is just the first in a new family of high-power laser diodes to be launched by the company. For example, now sampling to customers is a 783 nm device with an output power of 5 W that could be used to pump thulium-doped fiber lasers.

According to Marsh, achieving 5 W at 783 nm required clever engineering at both chip and package levels. At the chip level, the device exploits Intense's QWI technology to avoid reliability problems associated with catastrophic optical mirror damage, as well as HPD's asymmetric waveguide technology to increase the power and reliability of the devices.

This asymmetric waveguide technology works by spreading the optical energy into a longer waveguide to reduce the optical power density in the laser's active region. Marsh says that this approach is particularly beneficial at 8xx wavelengths, where power degradation becomes a real problem at high output powers.

Also new for Photonics West is the Power Pack 630 fiber-coupled laser module, a turnkey solution that combines a 630 nm laser with cooling elements, a monitor photodiode, and a thermistor. The module delivers 2.5 W at 630 nm, an important wavelength for medical applications such as photodynamic therapy, and Marsh says that the integrated approach adds more value to end customers - particularly those who are unfamiliar with laser technology.

The next step will be to incorporate QWI technology into the chip design, which Marsh claims will double the output power at visible wavelengths. At that point, he says, display applications look more promising - particularly if the lasers can be produced in volume to bring prices down.

It was the first day of the Photonics West exhibition today, which meant that I was juggling my time between the conference sessions and stopping by booths to see the latest product developments. Here's a quick summary of some of the things that caught my eye on the Toptica Photonics booth (number 427).

First up, the company has launched a picosecond ytterbium fibre laser designed for seeding medical and industrial laser systems e.g. for ophthalmology, optical sampling and micro-machining. The FFI PicoFYb is an all-fibre system pumped by telecom diodes.

The company was also demonstrating a system that allows users to control the coherence length of a laser over nine orders of magnitude. One important application is stabilizing the frequency of a tunable diode laser. Thomas Renner of Toptica told me that linewidths below 1Hz could be realized but that, at the other end of the scale, the linewidth could also be broadened up to GHz ranges.

And the finale of my visit to the booth was an ultrafast pump-probe set-up that did not use a mechanical delay line. Here, a piezo actuator controls the cavity length of the probe laser, such that its repetition frequency is alternately lower and higher than that of the pump laser. According to Renner, the delay input enables the user to set and sweep the pulse timing anywhere within an 800 picosecond range and that sweep frequencies as high as 100 Hz are possible.

"Ultrafast lasers will become an industry worth $100 billion by 2015." That bold assertion was made by Scott Davison, president of ultrafast start-up Raydiance, speaking at today's Lasers and Photonics Marketplace Seminar.

Davison believes that ultrafast lasers have reached what he calls the "silicon moment" - the tipping point where miniaturization and automation enables the technology to be adopted in mainstream applications. This is the time, he says, when investment dollars transforms what starts off as a geeky enthusiasm into a relevant technology.

To hit the $100 billion mark, though, Davison advocates a radically different business model. Instead of laser firms recording one-off income from hardware sales, he says that ongoing revenues could be achieved by charging some sort of "royalty" every time the laser is used. I'm not convinced that it'll catch on.

Back in the real world, Andreas Tünnermann of the Fraunhofer Institute of Applied Physics in Germany showed just how far ultrafast lasers have come in the past few years. While ultrafast lasers have long shown huge potential for micromachining applications, early versions suffered from low repetition rates and low average power - which meant that it could take several minutes to drill a single hole.

Now, however, the introduction of ultrafast fiber lasers has increased the average power to tens and even hundreds of watts, while repetition rates have risen to hundreds of kilohertz. As a result, a hole in a 0.5 mm thick piece of stainless steel can be drilled in just 800 ms.

Dennis Matthews of the Center for Biophotonics Science and Technology at the University of California, Davis, then spoke about the opportunities for ultrafast lasers in bioscience and medicine. Matthews pointed out that sub-picosecond lasers have already become ubiquitous for bioimaging applications such as multiphoton fluorescence microscopy, and at the same time are increasingly being used to generate other forms of radiation, including X-rays, terahertz radiation, and even protons for radiotherapy treatment.

Matthews says that ultrafast lasers could also play an important role in laser therapy, particularly as more compact turnkey solutions become available. Cost issues remain, though: he reckons that the price tag for an ultrafast laser system will need to fall to $30-50k for dentistry applications and $70-100k for surgical use.

It's one of today's biggest debates: disk lasers vs. fibre lasers. It also proved to be a major dilemma for me this morning. With sessions called "Disk Lasers 1" and "Fiber Laser Market" running in parallel, it was a tough decision to pick one.

In the end, I opted for the fiber laser session and wasn't disappointed by talks from IPG Photonics, SPI Lasers and Aculight. I arrived 10 minutes before the session was due to kick off and got one of the last free seats in a crowded conference room running two projection screens to satisfy the large audience.

IPG

There was a tremendous buzz in the air as Valentin Gapontsev of IPG Photonics took to the stage. After a general introduction to the technology and its benefits, Gapontsev gave the audience some hard facts. By the end of 2007, IPG had shipped a total of 9000 fibre lasers. Breaking this down, between 2005 and 2007 IPG shipped a total of 560 kW-class lasers, with 220 of these being shipped in 2007. He continued by adding that 309 of the 560 kW-class laser were in mass production running 24/7 and had achieved a total of 1,280,460 operating hours.

Gapontsev then took the audience through a whirlwind tour of existing and emerging applications of fibre lasers. This included everything from patterning solar cells and rapid laser patterning to remove the ITO layer used in flat panel displays to remote welding in automotive applications and high-speed cutting.

To demonstrate just how fast high-speed cutting can be, Gapontsev ran a video showing a singlemode 1 kW fibre laser cutting a 10x10 array of holes in a 50 micron thick sheet of metal. It took just 1.17 seconds to cut the 100 holes. "Wow" was the overwhelming reaction from the audience. That was also the reaction when he showed a new result: a 5 kW laser running singlemode.

SPI

Next up was Steve Norman of SPI Lasers, who discussed various marking and micro applications of fibre lasers. It seems that solar cells could be one of the next big things for fibre lasers as Norman also described how fibre lasers can be used for precision scribing and cutting silicon wafers.

Other applications under discussion included rapid manufacturing using laser sintering. The starting point in this case is a powder, which is irradiated by the fibre laser turning into a three-dimensional structure. This approach is said to be particularly useful for one-off parts such as dental crowns.

Aculight

There are applications outside of materials processing, as Robert Afzal of Aculight explained. First up was directed energy where Afzal said that fibre lasers offer an efficient and reliable route to electrically-pumped directed energy systems. The issue here is scaling up the power which can be done by either a spectral beam combining technique (similar to wavelength multiplexing in optical communications) or coherent combining (similar to phased antenna arrays). In both cases, beam quality is a key concern.

According to Afzal, Aculight is actively researching both beam combining methods and to date has achieved 522 W in a diffraction limited beam by spectral combining and 710 W by coherent combining.

Afzal also discussed active imaging, where the fibre laser forms an integral part of a 3D scanning LIDAR system. This application exploits the high-repetition rates and nanosecond pulse durations offered by fibre lasers emitting at eye-safe wavelengths.

All that and it's only 10am on day one!

In a year when steady single-digit growth is the norm in the photonics industry, any sector expanding by more than 30% year-on-year demands close attention. According to Greg Smolka, a consultant with 20 years experience of the photonics industry behind him, the market for optical coherence tomography (OCT) systems is benefiting from new technology that is opening up the IP landscape - and enabling more companies to enter the market.

In his talk at today's Lasers and Photonics Marketplace Seminar, Smolka pointed out that until 2006 the only player in the OCT market was Carl Zeiss, which introduced its first time-domain OCT system for ophthalmic imaging applications in 1996. Crucially, this first-generation technology was by covered a patent that prevented other players from launching competing products.

More recently, the introduction of Fourier domain OCT has fundamentally altered the competitive landscape. This technology improves both the accuracy and definition of images, and also increases scan speeds by a factor of 50-100. What's more, it's not covered by the original patent.

As a result, around 19 companies have launched commercial Fourier domain OCT products, and in so doing have extended the technique's capabilities from ophthalmology to other biomedical applications such as dentistry and cardiovascular imaging. According the Smolka, this will enable the OCT market to grow by 33.5% year-on-year, increasing from just less than $200m in 2007 to $800m in 2012.

So what is the opportunity for photonics firms? Smolka explained that each OCT system - which sells for anything from $50,000 for ophthalmic systems to $120,000 for cardiovascular applications - requires either an superluminescent or, increasingly, a 1310 nm tunable laser. Other optical components are also integrated into the system, including CCD or CMOS image sensors, galvonometers, and fiber-optic probes.

What's more, Smolka says that developers of OCT systems are typically focused on end applications, and are looking for technology partners to develop and supply the specialist optical components. One consequence, he says, will be an increase in the number of start-ups bringing new products to market, as well as significant merger and acquisition activity.

It's time for a change of tack here on my BiOS blog. With all of the postings so far restricted to the conference sessions, I'm in danger of overlooking the 150+ companies who were hard at it plying their wares at the BiOS trade exhibition over the weekend.

While blockbuster launches aren't really the order of the day at BiOS, the show still featured its fair share of innovative component, subsystem and OEM products for all manner of biophotonic applications. Among the new offerings to catch my eye was the ZoroLight LED multiplexer, a product that's being pushed for applications in fluorescence studies and high-throughput screening.

Developed by Bookham (Santa Rosa, CA), an optical component/subsystem vendor traditionally associated with telecoms and industrial markets, ZoroLight can incorporate up to six LEDs in a compact module (device length typically varies from 80 to 200 mm depending on the number of LEDs).

Bookham claims that its proprietary optical-filter technology means that ZoroLight takes up less space versus traditional free-space LED multiplexing modules but with comparable efficiency. What's more, "the use of LEDs is attractive due to their 10x to 20x longer lifetime compared to bulbs and their cost saving over lasers," says Ben Standish, ZoroLight product line manager.

Custom designs are available for volume OEM applications now, while standard designs are expected to be generally available in mid-2008.

Another neat subsystem launch is a family of white-light lasers from Toptica Photonics, Germany. There are three variants - widely tunable visible lasers, visible supercontinuums and IR supercontinuums - all combining "the brilliance of lasers and the bandwidth of lamps" (at least that's what the press release says).

For its part, TOPTICA is lining up applications in microscopy and expects the flexibility in wavelength to be exploited in two-colour experiments and time-resolved photon counting, for example. The broadband supercontinuums are generated in photonic-crystal fibres or highly nonlinear fibres, while individual lines can be extracted from the visible supercontinuum by using acousto-optical tunable filters.

According to the spec sheet, the total power in the infrared supercontinuum (range 1000-2100 nm) is typically 150 mW; the tunable visible laser has a bandwidth of 1 nm, a tuning range of 485-700 nm, and power between 1-10 mW; the visible supercontinuum spectrum ranges from 530-1000 nm with a total power of typically 40 mW.

At the system level, meanwhile, one of the more notable launches is the femtOgene laser microscope, billed as a "unique optical tool for nanobiotechnology, gene therapy and stem-cell research". Developed by JenLab, Germany, in collaboration with Austria's Femtolasers Produktions, the femtOgene is described as an ultracompact scanning nonlinear optical microscope with galvoscanners for beam scanning and focusing optics equipped with large-NA objectives (40x/1.3).

The instrument is based on a sub-20-femtosecond near-IR laser with high-order dispersion compensation, a technology that's said to overcome the problems of beam fluctuations observed in femtosecond laser systems based on prism technology. Specific applications for femtOgene will include optical "nanoinjection" of macromolecules; optical knock-out of cell organelles; and intracellular chromosome dissection.

That's all for today as I'm off to do some networking at the BiOS/Photonics West delegate reception this evening. More BiOS product news will be posted on the blog later this week, most likely when I get back to the office in Bristol.

Joe McEntee, editor of medicalphysicsweb.org

On Sunday, prompted by Rox Anderson's talk at the Hot Topics session (see previous post, "Looking for some hot stuff..."), I went along to listen to a couple of invited papers in a dedicated BiOS session on mechanisms for low-light-level therapy.

First up, Darayash Tata of the US Food and Drug Administration reported on an in vitro study of laser-induced modulations of the metabolic activities of malignant human-brain-cancer (glioblastoma) cells.

Tata and fellow investigator Ronald Waynant evaluated the efficacy of two light sources: a continuous-wave 633 nm wavelength helium-neon laser and a 1552 nm pulsed picosecond laser. During the study, glioblastoma cells were exposed in their growth-culture medium at several energy doses, with cellular metabolic activities measured via colorimetric assay three days after photo exposure.

Taken together, said Tata, "our findings reveal that optical or near-infrared low-level light exposures could potentially be a viable tool in reducing the metabolic activity of cancers."

In terms of a working hypothesis, the current thinking is that laser-induced changes in metabolism may result from laser-generated production of hydrogen peroxide (a natural by-product of cell respiration). More research is needed, however, to work out the exposure parameters that would optimize metabolic and cellular-growth suppression in vivo.

A second invited paper, presented by Juanita Anders, a professor in the department of anatomy, physiology and genetics at the Uniformed Services University of the Health Sciences (Bethesda, MD), highlighted the regenerative effects of laser light in the treatment of spinal-cord injury (i.e. severe central-nervous-system trauma for which there are currently no treatments).

Worldwide, it's estimated that there are 2.5 million people living with spinal-cord injury, with 130,000 new cases reported annually. All told, that equates to billions of dollars in acute and long-term care.

In recent years, Anders and her colleagues have carried out a number of light-therapy studies on rat models with spinal cord injury. The group's latest in vivo data, presented here at BiOS, demonstrate that light delivered transcutaneously promotes regeneration of axons (nerve fibres) and functional recovery.

It's early days, but Anders reckons the results are further evidence that low-level light is emerging as a "promising non-invasive therapy for acute spinal-cord injury".

Joe McEntee, editor of medicalphysicsweb.org

Counterfeiting is a major problem in many industries. Enter French firm Amplitude Systemes and its collaborators, who have developed an internal engraving system for transparent materials that makes use of a femtosecond laser. The system is the end result of a project called NAGINELS, which stands for non-aggressive glass internal engraving laser system.

According to Eric Mottay of Amplitude Systemes, the aim of the system is to engrave a code on the primary glass container - which could be, for example, a perfume bottle, a syringe for use in the pharmaceutical industry or even a bottle of champagne.

"The key requirements are that the laser should have no impact on the glass, no impact on the substance/liquid enclosed in the glass and be tamper-proof," said Mottay. "Sources such as CO2 lasers engrave the surface. Nanosecond laser pulses allow internal engraving but they also create micro-cracks in the glass which can cause the product to deteriorate."

The NAGINELS instrument uses a ytterbium diode-pumped amplifier system emitting 500 femtosecond pulses to write a datamatrix into the glass. This datamatrix is essentially an array of tiny squares in pre-determined pattern. The idea is that the datamatrix is discrete so an array measuring 1x1 mm could be present somewhere on a bottle for example or a smaller 60 x 60 micron array could be written into a syringe.

In the fourth quarter of 2007, the project partners set up a company called TRACKINSIDE to commercialize NAGINELs technology.

Monday 11.00 PT: You've got to feel some compassion for the people aiming to call the photonics and laser market for 2008. At today's Lasers and Photonics Marketplace Seminar, Steve Anderson, editor-in-chief of Laser Focus World, prefaced his annual forecast of the laser market with the following words from Stanford economics professor Ezra Solomon: "The only purpose of economic forecasting is to make astrology look respectable."

And there's no doubt that the effects of instability in the US economy - and increasingly the global financial marketplace - has introduced even more uncertainty into what has always been an inexact science. According to Anderson, the biggest unknown is how falling consumer confidence, particularly in the US, might impact on global laser sales.

The good news, he says, is that for the moment at least it appears that high-tech firms have been shielded from the broader economic malaise. Figures released by Anderson show that sales of all types of lasers increased by around 9% in 2007 to reach $6.9 billion. He also forecasts continued growth in 2008 - albeit at a lower rate of 7% - which will bring the total laser market to $7.3 billion.

Beyond that headline figure, Anderson says that sales of non-diode lasers rose by 8% in 2007 to account for $3.08 billion of the total, driven primarily by materials processing applications as well as double-digit growth in lasers for scientific and medical applications. That growth rate is expected to decline to 7% in 2007, in part due to weakening markets in lasers for materials processing in microelectronics. Looking at the detail, one interesting prediction is that sales growth for fiber lasers is expected to slow from a massive 39% in 2007 to a more modest 16% in 2008.

For diode lasers, revenues grew by 10% in 2007 to reach $3.81 bn, buoyed by a rapid expansion in FTTx deployments. According to Bob Steele of Strategies Unlimited, growth is likely to slow to 7% in 2008 - for the first time breaking through the $4 billion mark - with gains expected in 405 nm lasers in next-generation DVD systems and high-power laser diodes for fiber laser pumps. However, Steele also cautioned that declining customer spending could impact sales of laser diodes into consumer electronics applications.

Sunday 22.30 PT: Yesterday evening I joined over 500 hard-core biomedical-optics types for what's become something of a BiOS institution. I'm referring to the Hot Topics session, an annual event that's renowned as much for its beyond-the-call-of-duty timing (7 till 9.30 p.m. on conference Saturday) as for the masses of factual and quantitative information that speakers are required to cram into a 10-minute speaking slot.

Time - or rather the lack of it - precludes anything like a comprehensive write-up of all the Hot Topics. Instead I'll focus on a couple of papers that I think showcase the wide-ranging therapeutic and diagnostic potential of clinical photonics.

Rox Anderson, professor of dermatology at the Wellman Center for Photomedicine (Boston, MA), got the session started with a review of the latest advances in therapeutic lasers. He reckons that optical therapies are "poised for huge impact" and encouraged the audience to use BiOS and Photonics West to "network with MDs, heck even talk to me".

Over the years, Anderson and his colleagues have pioneered all manner of laser treatments - among them selective photothermolysis for the treatment of vascular birthmarks without scarring, as well as lasers for tattoo removal and permanent hair removal. His group is currently working on laser targeting of other skin structures, such as sebaceous glands, sweat glands and fat (see Free-electron lasers: ready to shine on medicalphysicsweb).

Anderson is particularly excited by progress in microbeam laser treatments. Here an array of invisibly small burns (or "little murders") are delivered to diseased skin tissue in such a way that it is possible to "tune" the depth of the beams. Future applications could include laser-surgery treatment for cancers of the larynx, lung, brain, bladder and breast.

Another area singled out for attention was low-level laser therapy, with Anderson citing impressive results published in the journal Stroke on the efficacy of infrared laser therapy as a new treatment strategy for ischaemic stroke (Stroke 2007 38 1843).

Subsequent Hot Topic papers, in the main, concentrated on the diagnostic capabilities of photonics. Mary-Ann Mycek, associate professor in the department of biomedical engineering at the University of Michigan (Ann Arbor, MI), provided a neat case study with a talk entitled "Probing pancreatic disease using tissue optical spectroscopy".

Pancreatic cancer is the fourth leading cause of cancer death in the US and has a five-year survival rate of only 4%. The biggest problem is late detection - due in large part to the inaccessibility of the organ, which complicates diagnosis via conventional radiological procedures (e.g. ultrasound, CT and MRI).

Subsequent treatment comprises lengthy and complex surgery, after which many patients turn out to have pancreatitis (a treatable inflammation of the organ) rather than pancreatic cancer. For any would-be optical interrogation scheme, the task is therefore to differentiate a cancerous organ from one affected by pancreatitis.

With this in mind, Mycek and her colleagues have studied fluorescence and reflectance data for normal and diseased pancreas tissue. In what's claimed to be the first limited pilot study to optically probe freshly excised human pancreatic tissue and in vivo human xenografts in mice, they observed increased reflectance from cancer cells (versus normal tissue and tissue exhibiting pancreatitis).

They've linked this behaviour to changes in optical scattering properties caused by the increased size of the cell nucleus in cancerous tissue. "Although the preliminary studies are small, optically detectable biomarkers appear to be consistent with disease progression," noted Mycek.

The other Hot Topics papers covered a diverse range of subject matter. Specifically:

• Monitoring and predicting chemotherapy using diffuse optics

• Imaging and treatment of cancer using gold nanoparticles

• Photoacoustic microscopy and computed tomography

• Real-time quantitative microscopy on the nanometre scale

• Multidimensional fluorescence imaging

• Single-molecule super-resolution imaging and trapping

• Spectroscopy for diagnostic and interstitial photodynamic treatment control.

Joe McEntee, editor of medicalphysicsweb.org

While Joe was doing the hard work at BiOS, Jacqueline and I flew into San Francisco ahead of the main Photonics West event. After being confined to an airplane seat for the best part of 11 hours, we thought the perfect antidote would be to head down to Pier 39, hire a couple of bikes, and ride over the Golden Gate bridge.

It was well worth it. The people at the aptly named Blazing Saddles bike rental equipped us with bikes, an elastic band as a cycle clip, and a map showing us the way to the bridge. Notwithstanding the fact that the brakes on American bikes are the opposite way round to those in the UK, and some dodgy gear levers, we made it to the bridge in record time (well, for us anyway) - just in time for us to see the sun set over the bridge and the ocean beyond.

Sunday 09.00 PT: The US National Cancer Institute's Network for Translational Research in Optical Imaging is a multicentre programme tasked with realizing practical optical modalities for early cancer detection, cancer diagnosis and measurement of response to therapy. Yesterday evening I went along to a dedicated BiOS session to hear about the network's efforts in applying diffuse optical imaging for enhanced detection of breast cancer.

Brian Pogue, associate professor of engineering at Dartmouth College (Hanover, NH), kicked off the session by reviewing the integration of near-infrared spectroscopy (NIRS) into standard MRI and CT instrumentation. While this type of hybrid imaging is still in its infancy, he reckons that using it to guide therapy or to properly individualize the choice of therapy is "the next logical step".

With this in mind, Dartmouth researchers, in collaboration with Philips Medical Systems, have developed a prototype small-animal imaging system that integrates NIRS into a 3 T MR breast biopsy coil.

"We use MR for imaging, NIR for spectroscopy," said Pogue, adding that such an approach allows quantification of molecular tracers and biophysical imaging of tissue using contrast mechanisms that are not otherwise available.

Right now, however, the optical-fibre interface (for light delivery) is too cumbersome for the clinical setting, while the cost of integration takes optical spectroscopy out of the "inexpensive category".

Soren Konecky of the University of Pennsylvania (Philadelphia, PA) provided an alternative take on the multimodal theme. His presentation reported on a small pilot study (17 patients) to evaluate the coregistration of diffuse optical tomography (DOT) and PET images of the human breast.

The purpose here is not primary detection of breast cancer, rather the evaluation of a patient's response to therapy and early identification of resistance factors during treatment - information which can be used by doctors to adapt the treatment plan accordingly.

Unlike CT, MRI and ultrasound, DOT and PET primarily measure the physiological characteristics of tissue, rather than its anatomical structure. So why use optical and PET modalities in tandem?

"The combined analysis of optically measured parameters, such as haemoglobin concentration/oxygenation and blood flow, with PET parameters, such as fluoro-deoxyglucose uptake as a measure of glucose metabolism, may provide new and important information," notes Konecky's conference abstract.

He adds that "coregistration of DOT and PET parameters affords a method for increased tumour sensitivity and specificity compared to the stand-alone modalities."

Joe McEntee, editor of medicalphysicsweb.org

Sunday 06.00 PT: As promised, here's a brief report on the PDT sessions I attended yesterday. First up, Anna-Liisa Nieminen of the Medical University of South Carolina (Charleston, SC) presented the latest results of a collaboration with Case Western Reserve University (Cleveland, OH). Nieminen and her colleagues are currently evaluating the relative performance of two types of cell organelles - lysosomes versus mitochondria - as binding sites for PDT photosensitizers.

"It is often found that mitochondrion-bound photosensitizers are more effective than lysosome-bound ones," Nieminen told BiOS delegates. The phthalocyanine photosensitizer Pc 4, for example, binds preferentially to mitochondria and endoplasmic reticulum and upon photoactivation induces apoptosis with high efficiency.

However, the Case-South Carolina researchers have synthesized a series of Pc 4 analogues, including a molecule called Pc 181 that appears to be taken up into human cancer cells more efficiently than Pc 4. What's intriguing about Pc 181 is that it binds preferentially to lysosomes (intracellular structures containing digestive enzymes) and is more efficient at overall cell killing than Pc 4.

Those unique properties, she added, may offer insights into the killing of cells via lysosomal photodamage and ultimately to "new photosensitizers providing much better cell kill power".

Later, the session chair, Charles Gomer of the Children's Hospital Los Angeles, CA, presented a paper entitled "PDT effects on the tumour microenvironment: growing evidence for a combined-modality approach". Gomer is interested in how PDT can induce significant changes within the tumour microenvironment, changes that can lead to an angiogenic and/or a survival response.

A case in point is a molecule called survivin, a member of the inhibitor-of-apoptosis family of proteins, which is increased and activated in tumour cells and tissues following PDT. "Does PDT-mediated expression of survivin modulate treatment responsiveness?" he asked.

Gomer presented data confirming as much and concluded that a multimodality treatment approach that switches off the expression of survivin will lead to increased PDT efficacy.

Joe McEntee, editor of medicalphysicsweb.org

Saturday 18.00 PT: Day one of BiOS has been a full-on affair - so full on, in fact, that there's barely time for me to make my excuses before I head back to the convention centre for the weekend's main event: the BiOS Hot Topics session (which runs from 7 till 9.30 tonight). For now, a headline take on Saturday is about all I can manage.

Photodynamic therapy (PDT), a technique that uses a light-activated drug to kill cancer cells, was one of the main themes in today's programme. I went along to hear a couple of invited papers on PDT effects in the tumour microenvironment, as well as catching a "bigger-picture" perspective on the impressive clinical efficacy of PDT in the treatment of early- and later-stage head-and-neck cancers.

One double espresso later (to keep the jetlag in check) and it was time to switch codes from therapeutics to diagnostics. The US National Cancer Institute's Network for Translational Research in Optical Imaging provided the content for a dedicated session reviewing progress in multimodality imaging for breast cancer, with specific emphasis on the use of diffuse optical imaging in combination with established clinical modalities like CT, MRI and PET.

I'll post more details on the above tomorrow morning, plus news and views from the Hot Topics session to follow later on Sunday.

Joe McEntee, editor of medicalphysicsweb.org

As the optics.org team gears up for this year's Photonics West, we're busy planning our schedules to bring you the most significant technical innovations and commercial developments that will be announced at the show. And we've got plenty to choose from, with more than 1000 exhibitors on the show floor, four major technical conferences, as well a host of short courses, panel discussions and plenary sessions. If you've got a hot tip, please let us know by adding a comment or visiting us at the show at Booth #1135.

We'll be kicking off the blog in earnest at the weekend, when the BiOS conference and exhibition will be offering delegates a unique insight into the use of photonics in biology and medicine. After that, remember to check back here for regular postings from our editors at the main Photonics West event.