Laser video projector

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A laser video projector takes a video signal and modulates a laser beam in order to project a raster-based image. laser light shows use a vector-based system of rendering a pattern so are not appropriate for video projection.

1 Assembly
- 1.1 Modulating the Laser Signal
- 1.2 Horizontal and Vertical Refresh
2 Applications
3 Concepts
4 See also

[edit] Assembly

[edit] Modulating the Laser Signal

The video signal is introduced to the laser beam by an acousto-optic modulator (AOM) that uses a photorefractive crystal to separate the beam at distinct diffraction angles. The beam must enter the crystal at the specific Bragg angle of that AOM crystal. A piezoelectric element transforms the video signal into vibrations in the crystal to create a diffraction grating.

The first order diffraction signal is used and the other beams discarded.

[edit] Horizontal and Vertical Refresh

A rapidly rotating polygonal mirror gives the laser beam the horizontal refresh modulation. It reflects off of a curved mirror onto a galvanometer-mounted mirror which provides the [[refresh rate|vertical refresh].

[edit] Applications

Laser video projection is primarily used for large-dome flight simulators in which the brightness of conventional LCD projectors do not accurately represent real life conditions--the image is so far from the projector that high-powered lasers are necessary to achieve this brightness. Even so, the expense and power requirements of laser projectors limit their use to providing the area of interest directly in front of the simulator cockpit, with the side and ancillary views composited with other conventional projectors.

Theoretically, a high-powered laser projector can display a video image hundreds of feet away on large objects such as buildings and cliff faces.