Phase modulation control for an interferometric fiber optic gyroscope

A FOG (fiber-optic gyroscope) scale factor control has been developed by implementing a second-phase modulation producing an error function. This error function is used to drive the first original modulation depth, forcing J/sub 0/(M) to zero. A reduction factor of 100 in scale factor error is accomplished with a 0.1% loss in the SNR (signal-to-noise ratio) of the rate signal. The implementation of this control loop can be applied in a straightforward manner to a phase-modulated FOG. Therefore, an open-loop FOG can be used for more stringent applications such as attitude and reference.<>