A novel approach in fiber-optic gyro (FOG) technology was developed and incorporated into a strapdown inertial measurement unit (IMU). In this approach, optical switches are used to multiplex a single light source, detector, and electronics among three FOG axes. The multiplexed operation of the FOG triad extends the inherent advantages of the single-axis FOG to attain small size, light weight, and low power dissipation and provides a high-performance low-cost IMUs with improved reliability and reduced random drift. A scheme of the triad system is presented.
Jerry L. Page,
"Multiplexed approach for the fiber optic gyro inertial measurement unit", Proc. SPIE 1367, Fiber Optic and Laser Sensors VIII, (1 February 1991); doi: 10.1117/12.24733; https://doi.org/10.1117/12.24733