Development of Fiber Optic Gyroscope Sensing Coils with Improved Thermal Stability

Polymer coated optical fiber is anisotropic. When gyro sensing coils are made with this material, temperature induced stress limits the gyro performance. Extreme temperature cycles cause coil distortion and delamination of the fiber windings from the core material. There is no core material which improves this situation. At the gyro level, the symptoms include temperature induced scale factor, bias and axis alignment instabilities. Optiphase has conceived an innovation which decouples the fiber axial and radial thermal expansion terms, providing a unique solution to the gyro coil temperature problem. In Phase I, we propose to prove the feasibility of this approach. We will fabricate thermally compensated sensing coils less than one inch in diameter capable of < 1 deg/hr bias performance. The fabricated coils will be evaluated over temperature (-65C to +100C) for mechanical stability and optical performance. In Phase II, we will perform a parametric analysis to determine an optimum configuration for our approach. Numerous coils will be fabricated (enough for meaningful statistics), and verified over environment within gyro circuits. Also, a detailed set of coil fabrication processes and procedures will be developed. A small-volume low-cost fiber gyro, with its inherent ruggedness, long-life and high accuracy is highly applicable to commercial markets involving automotive, aviation, navigation & control, industrial control, autonomous robotics, and tracking antenna systems.