Abstract: A data signal processer processes a pair of phase quadrature signals responsive to an interference pattern indicative of the phase change between counter-propagating laser beams in a rotation sensor. The data signal processer provides an output pulse for each .pi./2 phase change between the counter-propagating laser beams of the sensor.

Abstract: A laser gyro built in test apparatus. A laser gyro includes a microprocessor which provides a high speed method of communicating test data to an external inertial navigation system. The microprocessor performs tests on the gyro including temperature sensor tests, dither drive tests, active current control tests, and reports on the expected life of the gyro. The gyro can be commanded from the external system to perform any number of the built in test functions. The built in test functions are periodically executed to evaluate the health of the laser gyro and are thereby incorporated in the monitor control loop of the laser gyro.