Fiber optic security system

摘要

An optical fiber security system includes an optical emitter connected to one end of an optical fiber and a detector connected to the other end. A random signal generator triggers the emitter to output a light pulse signal through the fiber. This generator also simultaneously triggers the detector to receive the light pulse signal. A comparator compares the light pulse signal that is received by the detector with an optimum reference to adjust and conform the emitter output with the reference. Also, a monitor determines whether a particular identifiable characteristic of the light pulse signal is within a predetermined range of values. Whenever there is not a simultaneous emission and detection of the light pulse signal, or whenever the light pulse characteristic is outside the predetermined range of values, the system alarms.