Thermal Strain in Lightweight Composite Fiber-Optic Gyroscope for Space Application

Thermal strain significantly affects stability of fiber optic gyroscope (FOG) performance. This study investigates thermal strain development in a lightweight carbon fiber-reinforced plastic (CFRP) FOG under thermal vacuum condition simulating space environment. First, we measure thermal strain distribution along an optical fiber in a CFRP FOG using a Brillouin-based high-spatial resolution system. The key strain profile is clarified and the strain development is simulated using finite element analysis (FEA) to understand the mechanism of the strain development. Several materials for FOG bobbins are then quantitatively compared using experimentally validated FEA from the aspect of the thermal strain and the weight to illustrate the clear advantage of CFRP. Finally, a hybrid concept combining low thermal conductivity polyacrylonitrile-based (PAN-based) CFRP and high stiffness pitch-based CFRP is proposed to minimize the thermal strain with minimal weight.