Special Features:

Cognizant service - united kingdom royal air force

Properties:

A device containing one or more light sources (either incandescent, glow, or solid state, lamps) opticallycoupled to one or more semiconductor type photo-sensitive elements, all of which are contained in an opaque enclosure. Light generated within the device by the application of an appropriate electrical input to the light source(s) acts upon the light sensor(s) to produce a corresponding output or change in some electrical quantity or variation in some electrical property. For items in which the light in directed at another item and the reflected light is interpreted (read) see scanner, optical.