GERAET ZUR MESSUNG DER PHASENMODULATION IN EINEM OPTISCHEN WELLENLEITER

摘要

A fibre-optic gyroscope, or other apparatus for measuring phase modulation, has a source 1 of frequency modulated radiation which transmits radiation to opposite ends 5 and 7 of a coil 11 of optical fibre the length of which is one half wavelength. Radiation emerging from each end of the coil 11 is combined with reference radiation, derived by reflection from radiation supplied to the opposite end of the coil, and is supplied to respective homodyne detectors 21 and 31. The 3rd and 4th order harmonics are compared in amplitude to produce signals representing the phase shifts produced when the coil is rotated about its axis. After averaging in a comparator 40, a signal is derived representing rotation rate. <IMAGE>