Abstract

The Optical Reference Gyro (ORG), a dry-tuned two-degree-of-freedom gyroscope, has a light beam emanating from its rotor along the rotor spin axis. The goal was to measure and improve the performance of this beam for use in inertially stabilized pointing systems. The isolation of the beam from gyro case disturbances is investigated. It was found most of the rotor-to-case coupling is due to gas torques. The noise in the beam is characterized. It was found nearly all of the noise is contained at the spin frequency. The rest of the noise is primarily made up of spin-frequency harmonics, light source noise, air noise, and gas noise. The design, construction, and performance of two types of a special phase-locked loop notch filter that removes the spin-frequency noise is described. One type electronically subtracts the noise from the signal, and the other torques the ORG rotor to remove the noise. It was found this notch