Infrared video cameras are nice, but the built in infrared LEDs tend to be fairly weak, especially over long distances. This is an inherent weakness of most light sources; the beam diverges quickly, spreading out far enough to be useless at a distance. Lasers, however, naturally emit coherent light over great distances.

A dot isn't particularly useful for illumination, but the beam can be spread in a controlled manner. A pair of cheap lenses linked to the camera's zoom can ensure the laser creates a spot matched to the camera's field of view. The laser could even share the camera's lens system, though care must be taken to prevent internal reflections from exposing the sensor directly.

The laser will have to be fairly high powered for decent illumination, but the beam will never be concentrated enough to cause eye damage.
-- Aq_Bi, Feb 26 2010

More interesting, if less efficient, would be to have the laser remain a dot but scan the area many times a second. This would reduce the frame rate, but increase the resolution.

You could possibly do away with the camera mechanism entirely. Have a single LDR filtered for exactly the right frequency, and just read the signal it gets from the columnated laser reflections.
-- mitxela, Feb 26 2010



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