FIBEROPTIC GYROSCOPE WITH PASSIVE PHASE DETECTION FOR LOW-COST APPLICATION

In this paper a passive fiber optic gyroscope without nonreciprocal ph ase modulation is presented. A fused fiber 3 x 3 directional coupler p rovides a constant phase shift thus enabling the detection of rotation rate at the quadrature point. Bias and scale factor errors due to ind eterministically changing birefringent coupling centers in the non-pol arisation preserving monomode fiber coil are eliminated by using a con trast insensitive signal recovery scheme. A simple temperature compens ation procedure has been implemented in the gyro software which yields a bias stability of less than 0.04-degrees/s and scale factor errors of less than 0.5% in the whole temperature range from -40-degrees-C to + 70-degrees-C.