Ordinary visible light is scattered by haze but infrared(IR) radiation can penetrate through the haze without being scattered.Therefore,these can be used as signals on distant objects obscured by atmospheric haze.Also,IR radiation enables sharpshooters to see their targets in total darkness.These devices essentially consist of an IR lamp which sends a beam of IR radiation (called black light) and a telescope receiver which picks up returned radiation from the object and converts it to a visible image.

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