Fiber optics security system

Abstract

Closed loop fiber optic link means, transferring energy from a radiant source to a receiver, includes serially connected fiber optic links and detectors. Energy cessation causes alarm. Detectors include: (1) A pair of optical transducers oriented whereby light, air transmitted, is received with insignificant loss. In water, light received is so insignificant that energy to the receiver ceases. The first transducer provides a light beam within a constant index of refraction medium to the second transducer spaced and oriented to ordinarily receive the light beam. When light passes through media having different refraction indices at non-normal angles, light is refracted whereby receiver energy ceases. The transducers are oriented in a straight inclined path. (2) Optical fiber, stable to approximately 135.degree. F., which melts above approximately 155.degree. F., provides fire detection. (3) A bimetallic element attached to one of axially aligned optical fiber holders, when heated, mis-align the fibers. A snap action bimetal device displaces at a specific temperature. (4) A connector holds optical fiber and condensing lens for narrow light beam emergence. A second connector, holding the end of a second fiber in proximity to a second lens focus, is axially aligned with the first so that the second fiber transmits light. Opaque objects therebetween interrupt the beam causing energy cessation. (5) Opening of an entrance device having optical fibers coupled in axial alignment to opposite sides thereof causes the fibers to mis-align, causing energy interruption. The radiant energy source and receiver are in proximity to each other.

Dependencies are inferred from the claim text.