Abstract:Aiming at the static and dynamic measurement of oil film thickness, a precision displacement detection system based on the reflective light intensity modulated coaxial fiber optical displacement sensor (RLIM-FODS) is designed in this paper. The mathematical model is established according to the characteristic of the light field of laser beam approximate to Gaussian distribution, and the characteristic function is simulated and analyzed by using Matlab, the partial background light of the photoelectric conversion is effectively compensated, the offset voltage adjustment and the cut-off frequency simulation and correction of the filter circuit are carried out, and is verified by experiment. The simulation and experimental results show that the model can effectively reduce the impact of the power supply fluctuations, micro bending loss and so on, the signal detection circuit can accurately amplify the small signals, and the output signal is stable, low noise, small offset, the linear interval is in the range of 1200~2700μm, and the sensitivity is up to 6mV/μm, which meet the requirements of precision detection.