According to the Scientific Information Agency FIAN-Inform, the RAS Institute of Physics named after P. Lebedev completed yet another stage of creation efficient lasers for projection television-powerful and concurrently miniature light sources, forming tricolor RGB (red-green-blue) pixels (elements of a digital image). The operating principle of such devices consists in a logical development of an electron-beam tube, where luminescent material is replaced by a semiconductor crystal.
The idea of this innovative design also originated at the FIAN, in particular, it belongs to Acad. Nikolai Basov, to Oleg Bogdankevich, Dr. Sc. (Phys. & Math.) and Alexander Nasibov, Dr. Sc. (Tech.). As early as in 1967 they proposed to use a laser electron-beam tube to produce a record-breaking powerful light current (12,000 lm). In the 1980s, the Scientific Research Institute Platan (Fryazino, Moscow Region) in cooperation with the FIAN transformed this tube into the first laser display Kvantoskop, irradiating red, green and blue bands. The color "image" was formed in it by way of combining three monochrome HD images on the display with an area of around 100 m2. But the equipment was too big to handle and required cooling of a semiconductor layer to low temperatures (-120 °C). The task was to get a high capacity light at room temperature.
Science in Russia, No.3, 2012
Laser electron-beam tube on monocrystals.
"Today arc xenon high-pressure lamps are mainly used as sources of light in projection devices," said Vladimir Kozlovsky, Dr. Sc. (Phys. & Math.), head of research at the Cathode Beam Laser Laboratory to FIAN-Inform. "But their efficiency ratio is about 1 percent... The point is that to obtain a high quality image, we have to "cut" relatively narrow lines of three main colors--red, green and blue--from the complete spectrum of such a lamp, and the remaining capacity of radiation of the device, which converts into heat, has to be taken away."
Some companies tried to replace such lamps by light-emitting diodes. But compared to the laser gear, they come short of light intensity, which means that several thousand lumen projector will additionally require an expensive lens system. Other producers (for example, US company Q-peak) tried to benefit from a source of light based on duplication and parametric conversion of frequency of solid lasers with diode pumping. However, according to the FIAN-Inform, these devices also have their own disadvantages, including a very high price.
As explained by Kozlovsky, today the market is moving towards picoprojectors combined with cell phones. "This means we can project all data contained in a cell phone to any paper or a wall. Of course, this is not a problem-free process: we already have lasers of required
Red laser characteristics (GalnP/AIGalnP nanostructure).
power, but they consume too much energy-no battery can 'feed' them." According to the scientist, it is necessary to improve characteristics of monochrome light sources. Many scientific teams are now engaged in this work, including his laboratory.
FIAN specialists focus their efforts on the development of lasers based on semiconductor nanostructures with cathodebeam pumping, containing numerous thin layers--quantum pockets located in a microresonator. This allows to work in terms of increased temperature, reduces significantly (to several kV) accelerating voltage and extends service life of the energy source. But the principal advantage of such lasers is their low price as compared with analogs.
Employees of Kozlovsky's laboratory working in close cooperation with colleagues from the RAS Institute of Radio Technology and Electronics named after V. Kotelnikov, RAS Fiber Optics Center and foreign partners from the Technological Center of Sheffield University (England) and Principia Light Works Inc. (USA) managed to achieve high performance characteristics (up to 12 percent at 40 keV) of a red laser (GaInP/AlGaInP nanostructure), proposed some variants of green and blue light sources. According to the FIAN-Inform, laser electron-beam tubes were already tested in the laboratory conditions: 9 W and 640 nm (red light), 3 W and 535 nm (green light) and 6 W and 458 nm (blue color). The red light tubes are almost ready for a serial production. The main objective now is to improve technology of production of nanosize structures for green and blue lasers. But this is a task for the next stage of work, which has already been initiated.
After materials of the Scientific Information Agency FIAN-Inform, January 19, 2012
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