Laser projector shows bright colors

Sharp, vivid images (left) are produced by a pulsed-laser red-green-blue (RGB) projection system (right) from the Corporation for Laser Optics Research (Portsmouth, NH). Even in a brightly lit environment, the picture remains clear, with a luminance of 4500 cd/m2. The 640 ¥ 480-pixel image is national-television- standard-code signal compatible and can run off of an ordinary VCR, cable television, or similar sources. It has been used to project a picture onto screens as large as 9 ¥ 12 f

Laser projector shows bright colors

Kristin Lewotsky

Sharp, vivid images (left) are produced by a pulsed-laser red-green-blue (RGB) projection system (right) from the Corporation for Laser Optics Research (Portsmouth, NH). Even in a brightly lit environment, the picture remains clear, with a luminance of 4500 cd/m2. The 640 ¥ 480-pixel image is national-television- standard-code signal compatible and can run off of an ordinary VCR, cable television, or similar sources. It has been used to project a picture onto screens as large as 9 ¥ 12 ft.

The laser beams are horizontally modulated by acousto-optic modulators and vertically scanned at 60 H¥using galvanometers. All three sources are operated at a 17-kH¥repetition rate. Red output is produced by a rhodamine dye laser that puts out approximately 12 W of power at 615 nm. The green source is a flashlamp-pumped, Q-switched Nd:YAG laser frequency-doubled with KT¥to 532 nm with power in excess of 40 W. Blue light with 5-W output at 450 nm is produced by a Nd:YAG-laser-pumped Ti:sapphire laser frequency-doubled with a lithium borate crystal.

The design is reportedly cost-competitive with existing large-screen projectors, and systems are scheduled for beta-site testing this fall. Company CEO Peter Chiasson expects full commercialization by the end of 1995. Future development efforts include conversion to entirely diode-pumped RGB sources.

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