Novel Reflex Fiber Optic Angular Displacement Sensor Based on Fiber Optic Arrays

A fiber optic sensor for two-dimensional angular displacement measurement is proposed. Linear light receiving fiber arrays arranged as a crisscross spoke are used in the sensor probe. The measured angular displacement variation will lead to the light spot position change, resulting in the light intensity variation received by each linear-arranged receiving fiber and will be recorded by the charge-coupled device (CCD). Based on the Gauss distribution theory, reflected light spot center can be determined by fitting a Gauss curve according to each received light intensity and the position of each receiving fiber. With this method, measurement errors caused by surface reflection index variation, light power fluctuation, and ambient light disturbance can be effectively avoided. The difference of transmission power loss of each receiving fibers reduce the measurement accuracy of this system. The proposed method based on the measurement and compensation of transmission power loss of fiber array can effectively improve the angular measurement resolution to 3.8 x 10(-4) rad.