Abstract: A pair of connectors that convert electrical signals into optical signals for transmission along an optic fiber, and that also convert optical signals received from an optic fiber into electrical signals, is combined with a two-optic-fiber cable to provide an interconnecting cable assembly that receives electrical signals from a sending apparatus at either end of the cable, and presents electrical signals to a receiving apparatus at the other end of the cable, although the intervening transmission is optical. One optic fiber optically links the electrical-to-optical converter (light emitter) in one connector to the optical-to-electrical converter (light detector) in the second connector, while the other optic fiber optically links the emitter in the second connector to the detector in the first connector; thus the cable assembly is bidirectional and may be laid down and connected in either orientation with equivalent performance.

Abstract: This security system monitors a remote intrusion-sensing unit by probing it with a probe signal that is randomly modulated. The intrusion-sensing unit replies with a composite signal in which "secure" or "alarm" status information is superimposed on the random modulation of the probe signal. (The system may if desired be elaborated to accept and utilize other status information, such as "access" or "reverse correlation.")A master unit checks the correlation of the reply-signal modulation with the probe-signal modulation, and generates a special "deception" alarm if the correlation is not in accordance with an established pattern--such as positive correlation, reverse correlation, or correlation varying in some way that is systematic or otherwise determinable by the master unit.

Abstract: Each of two optical fibers to be mated is cemented to one end of a respective quarter-pitch segment of graded-index rod, at the axis of the rod. The opposite end of each of the two quarter-pitch segments is polished flat, perpendicular to the axis. The two polished ends are faced toward each other and held in precise parallelism, but not necessarily touching, by a suitable connector housing. An optical signal from one optical fiber is collimated by its attached graded-index rod segment for transmission across the gap to the other rod, which in turn focuses the parallel rays onto the receiving tip of its attached optical fiber.A planar window, such as a pressure window of a deep-underwater craft, may be interposed between the two sides of the connector without disturbing performance.

Abstract: A metal ferrule is attached to the end of an optic fiber, with the ferrule end and fiber tip coplanar. The ferrule and fiber are slidably mounted in a housing which incorporates a quick-release connecting catch, and are abutted by spring-loading against a mating optical device. The catch is adapted to engage a fitting secured to the mating optical device.