| In free-space optical communication systems,using fast steering mirrors with large tilt angle to implement the coarse-fine pointing function of the Acquisition,Tracking,and Pointing(ATP)system can effectively reduce the system’s size and power consumption.Traditional angle measurement devices(such as eddy current sensors,capacitance sensors,resistive strain gauges,quadrant detectors,and positionsensitive detectors,etc.)are difficult to meet the measurement requirements of fast steering mirrors with large tilt angle.To address this issue,this thesis investigated reflective quadrant photoelectric detector(PD)angle measurement system in the fast steering mirror and conducted in-depth research on angle measurement algorithms and the impact of system parameters on the measurement range.The main research contents are as follows:1.Analyzed the angle measurement methods of various types of fast steering mirrors,explained the composition and working principle of the large-angle micro fast steering mirror system,proposed an overall scheme for the reflective quadrant PD angle measurement system,and analyzed the main performance indicators of mirror angle measurement.2.To clarify the measurement mechanism of the reflective quadrant PD angle measurement system,calculation models were established under Gaussian light model and LED(Light Emitting Diode)Lambertian radiation model.In order to improve the measurement accuracy of the system,the Dose Resp function fitting algorithm was proposed,and the correctness and effectiveness of the algorithm were verified through simulation.3.The definition of the maximum measurement range and linear measurement range of the system was clarified,and the impact of the distance between the detector and the light source,the distance between the mirror center and the light source,and the LED half-power angle on the maximum measurement range and linear measurement range of the system were analyzed.A method to improve the system’s measurement range was also proposed.4.Built a mirror angle measurement experimental platform to verify the correctness of the established solution model under the LED Lambertian radiation and the feasibility of the Dose Resp function fitting algorithm.The experimental results show that the reflective quadrant PD angle measurement system has a root mean square error of 0.018° within the mirror tilt angle range of ±10°,which meets the index requirements.Based on this,the correctness of the influence of system parameter changes on the measurement range trend was verified,guiding the design of system parameters and laying a theoretical foundation for further engineering applications. |
