Field Test of a Laser Signalling Device
HARRY DIAMOND LABS ADELPHI MD
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The report describes a test, under realistic field conditions, of the feasibility of using a small helium-neon gas laser as a visible signalling beacon. A 1.5-milliwatt laser beam with 2-milliradian beam divergence was clearly visible from the air at a slant range of 30 kilometers, against a bright sunlit background of river, forest, and marshland. The required aiming precision, optimum beam divergence, and narrow-beam secure nature of the laser beacon are discussed. The eye-hazard involved in the use of a laser signaller is shown to be quite small and probably controllable in a field environment. A prototype device that meets the requirement for a compact, light-weight, and self-contained long-range visible beacon is described.
- Optical Detection and Detectors