Rotation rate measuring instrument

摘要

A rotation rate measuring instrument is disclosed in which two light beams propagate through a coiled optical fiber in opposite directions. After passing through the optical fiber, the two light beams are combined and directed onto a photodetector. One of the light beams is phase-modulated in a phase-modulator before entering the optical fiber. The modulation frequency is fm. The output signal of the photodetector is fed to a variable-gain amplifier whose output signal is separated into a signal of frequency fm and a signal of frequency 2fm. The rotation rate is derived from the signal of frequency fm. The signal of frequency 2fm is applied to a detector whose output is fed to an operational amplifier. The other signal applied to the operational amplifier is a reference signal of amplitude UR. The operational amplifier controls the gain of the variable-gain amplifier in such a way that the output signal of the detector has the same amplitude as the reference signal UR.