Proton‐induced degradation in interferometric fiber optic gyroscopes

Abstract

Recent advances in Interferometric Fiber Optic Gyroscope (IFOG) technology have enabled these devices to equal, and in some respects exceed, the performance of the floated, spinning wheel rate integrating gyroscope. However, their ability to perform in a space radiation environment has been a significant concern. Test results are presented addressing the effects of space radiation on the performance of a high precision pointing grade IFOG. Proton-induced degradation of the optical components of an IFOG is evaluated based on testing performed at the Harvard Cyclotron Laboratory (HCL). Rationale is provided for using the HCL proton accelerator as a reasonable simulation of the space environment. An analysis is presented which prioritizes the component-level dose tests based on expected radiation sensitivities. The evaluation addresses both total dose (to about 12 krad) and dose rate effects. Testing was performed at the component level as well as the system level with an expanded version of a closed-loop operational IFOG. Primary concerns include permanent attenuation and spectral transmission (wavelength) sensitivity to total dose, and angle random walk and bias stability degradation as a function of dose rate. Component level results are presented for a superfluorescent light source, integrated optics chip (IOC), coupler, and polarization maintaining fiber coils. Closed-loop transient noise results are evaluated based on dose rate testing of the IOC, coupler, and fiber coil.