| 摘要 |
In a fiber optic gyro, a clockwise propagating light ray and a counterclockwise propagating light ray propagate in an optical fiber coil in a time of ?, and are given a bias phase modulation signal by a phase modulator connected at an end of said optical fiber coil, in such a manner that a phase shift increasing stepwise by .pi./2 radian every time interval T is applied n steps and then a phase shift decreasing stepwise by .pi./2 radian every time interval T is applied n steps, to the phase modulator. A signal generator generates a bias phase modulation signal every time interval T according to an oscillation frequency of a voltage controlled oscillator. An interference light beam of said clockwise and counterclockwise propagating light rays is converted to an electric signal by an opto-electric converter and, if the time interval T does not coincide with a propagation time, a positive- or negative-going pulse is created in an output of the opto-electric converter during a period for the bias phase modulation signal to increase or decrease. Such a positive- or negative-going pulse is detected by a pulse detector and, based on a detected result, an oscillation frequency of the voltage controlled oscillator is controlled so that said pulses no longer occur.
|
