By Chris Lee | Published: January 28, 2008
I spend a lot of my time writing about optics, but I usually focus on visible light or the infrared. This isn’t because I am not interested in ultraviolet light or even shorter wavelength light sources; rather, that really good light sources in this wavelength range are hard to find. It is really hard to perform extreme ultraviolet light experiments when you have no light source.
At present, the only good sources in this spectral range come from synchrotrons, which make them expensive—resulting in a very conservative approach to experiments. Now, some exciting new developments in generating extreme ultraviolet (EUV) and soft X-ray light offer the possibility of escaping the tyranny of the synchrotron.
There are two general methods for developing light sources in this color region: build a new laser or use a nonlinear medium to progressively change the color of an existing laser. Excitingly, new research indicates that combining the two approaches may be the best solution.
First, we’ll take a look at how an EUV laser is constructed, then how nonlinear optics for EUV generation works, and finish off by combining the two.
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January 25, 2008, San Jose, CA
I heard it again and again from most everyone I spoke to at SPIE’s Photonics West: The recession scare in the U.S. and the large stock-market drops in Europe and Asia are creeping into the otherwise solid, growing photonics marketplace. Just how much the ‘fear factor’ surrounding this economic uncertainty will affect the market going forward is anyone’s guess.
Several startup and mid-size companies are stepping back to evaluate the application areas that brought them the most success in 2007 as they chart a cautious spending roadmap for 2008. But taking a look at the ever-expanding attendance of Photonics West (and the need for two South Halls to accommodate the growing exhibition as well as the 2010 move to Moscone), the pessimism is hard to see.
Because much of the photonics industry is closely tied to consumer spending, recession fears are indeed real. However, there is every indication that factory automation trends and the biomedical market will continue to expand and hopefully buffer laser and optics manufacturers in the years ahead.
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Laser TV is a proposed new video display technology using laser optoelectronics. Although proposed as long ago as 1966, laser illumination remained too costly and too poor in performance to viably replace lamps except in some rare ultra-high-end projectors.
At the Las Vegas Consumer Electronics Show in 2006, Novalux Inc., developer of Necsel™ semiconductor laser technology, demonstrated their laser illumination source for projection displays and a prototype rear-projection “laser” TV.
First reports on the development of a commercial Laser TV were published as early as 2006-02-16 with a decision on the large-scale availability of laser televisions expected by early 2008.
On January 7, 2008, at an event associated with the Consumer Electronics Show 2008, Mitsubishi Digital Electronics America, a key player in the LED laser market, unveiled their first commercial Laser TV, a 65″ Full HD model.
A Laser TV requires lasers in three distinct wavelengths: Red, Green and Blue. While red laser diodes are commercially available, there are no commercially available green and blue laser diodes which can provide the required power at room temperature with an adequate life time. Instead frequency doubling can be used to provide the blue and green wavelengths.
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An experimental helmet is being tested by scientists as a treatment for Alzheimer’s disease.
It delivers low levels of infra-red light which researchers at the University of Sunderland believe may stimulate the growth of brain cells.
Tests in mice showed it improved learning ability and a study in humans is due to begin in the summer.
Current treatments for Alzheimer’s delay progression of the disease but cannot reverse memory loss.
The infra-red therapy was first developed to treat cold sores.
But when researchers studied how it worked, they found it stimulated growth of cells and may have applications in other conditions.
In tests in people with dementia using infra-red lasers, eight out of nine people showed some improvement, said Dr Gordon Dougal, a GP and director of Virulite, a medical research company based in County Durham.
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US researchers have made a nanolaser that could enable data to be stored with a density of 10 Tbit per square inch.
The nanolaser can focus light with a power of over 200?nW into a spot just 35?nm across. The result suggests that data storage beyond 10?Tbit per square inch could be possible at last.
“Furthermore, our nanolaser technology could be scaled down to a spot size as small as 10?nm,” team leader Sakhrat Khizroev of the University of California at Riverside told nanotechweb.org.
“This experiment could have a great impact on the magnetic data storage industry and especially enable so-called heat-assisted magnetic recording (HAMR) – one of the most promising data storage technologies of the future.”
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Laser technology is being used to locate potential archaeological sites hidden by woodland in Worcestershire, UK.
The hope is that ancient settlements and farms across the Wyre Forest will be detected by lasers fired from aircraft 3,300ft (1,000m) up.
The results are processed by computers and turned into images of the ground, currently hidden by trees.
One expert said the process offered a “tantalising glimpse” of a very dynamic landscape.
The Forestry Commission has teamed up with the Worcestershire Historic Environment and Archaeology Service.
The technique is known as Light, Detection and Ranging (LiDAR).
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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!
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Photonic Products, the UK optoelectronics device manufacturer and laser diode specialist, is pleased to announce that Sanyo’s tiny blue-violet laser diodes are now available in industrial strength and power: three new 405nm laser diodes which offer 20mW, 45mW or a massive 85mW optical output power, the highest power available in a single mode laser diode with an internal monitor photodiode.
This internal monitor photodiode, which can be used to accurately stabilise and control the optical output power, plus their stable beam structure, lower noise and lower current consumption, enables these new Sanyo blue-violet laser diodes to offer the performance required for critically demanding industrial and medical applications such as biomedical instrumentation, medical imaging, fluorescence, high-resolution printing, advanced DVD and industrial alignment.
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Cold Laser was proposed by Albert Einstein back in 1917. It sounded like something straight out of a science fiction novel to use low-level focused light waves as a therapy to heal tissue. But, just like most of his brilliant ideas Einstein was WAY ahead of his time.
It was 43 years after Einstein’s prediction that he was proven right and low-level light was first developed into a therapy.
In 1960, Hungarian surgeon, Endre Mester, first reported his experience using laser light to treat non-healing infections and inflammations (swelling) in rats. He reported a 70% success rate treating these infections which led to the development of a science he called “laser biostimulation,” or the stimulation of the local immune system. Today there is an entire science field devoted to this subject called photobiology, the study of how light affects living things.
It is extremely difficult to get a patent and market clearance from the FDA for anything related to health care. In February, 2002 the first patent and market clearance was given to a cold laser for the non-surgical treatment of carpal tunnel syndrome.
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Non-polar GaN substrates and low-defect crystal growth will have an important part to play in powerful, practical green laser diodes.
Nine research groups have begun tackling the challenge of producing a high-power 500 nm semiconductor laser in a three-year US-based research program called VIGIL.
The teams met to initiate the program at the end of November, and they have until June 2009 to hit the first milestone and produce a workable green laser based on GaN.
VIGIL stands for Visible InGaN Injection Lasers, a name that reflects the need to include high proportions of indium to obtain green light from GaN-based laser diodes.
“There’s a technical problem with getting green [light] out of nitride material,” explained Henrik Temkyn, VIGIL’s program manager at the US Defence Advanced Research Projects Agency (DARPA). “If you increase the amount of indium, the efficiency goes down.”
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