METHOD OF DEDUCING A SIGNAL OF A PHASE-MODULATED FIBER-OPTIC GYROSCOPE AND METHOD OF DETECTING A MODULATION COEFFICIENT

摘要

An AC component of the photodetector includes two quasi-sine waves in a cycle of phase-modulation. T1 and T2 are time lengths of the quasi-sine waves. When a fiber coil is rotating, T1 differs from T2. The difference between T1 and T2 is in proportion to an angular velocity of the fiber coil. This invention obtains the angular velocity by measuring time durations T1, T2 or both T1 and T2. Zero-crossing detection defines the moments of the beginning and the end of T1 and T2. Since this gyroscope depends on the measurement of time lengths, it is fully immune from the fluctuation of light power due to the light source, or the fluctuation of the gain in the electric circuit.