Design and Operation of a Transmissive Plastic Fiber Optical Displacement Sensor

Nowadays, optical fibers have a wide range of applications in the sensing field, especially in the displacement sensor. A Transmissive Plastic Fiber Optical Displacement Sensor (TPFODS) is designed, which achieves the displacement measurement by utilizing a cutting plate to modulate the light intensity. By performing an optical path simulation, the optical field distribution of the end of plastic optical fibers in different situations and the simulation curve of the relationship between the displacement and the light intensity are obtained. Furthermore, an experimental platform is set up, signal detection and processing circuit is designed. The experiments on light source stability and displacement measurement are conducted. The experimental results indicate the stability of the laser is poor and the error is up to +/-1.7%. In this condition, two methods have been adopted to improve the system accuracy: 1. using the high-frequency modulated light source; 2. introducing a reference signal to reduce the error caused by the temperature-drift. After optimization, the stability error is reduced from +/-1.7% to Error! Reference source not found.. The measurement system has a good linearity in the range of 1000 mu m-3000 mu m, and the measurement error less than Error! Reference source not found..