大口径自适应镜面微位移测量系统设计

Design of micro-displacement measurement system for large aperture adaptive mirror

针对大口径自适应副镜镜面变形量小、变化频率高、微变形难以精确测量的难题,设计一种基于电容检测芯片Pcap01-AD和STM32F103的镜面变形检测系统。首先,根据音圈电机驱动的变形镜的特点提出基于电容位移传感的变形镜微变形测量方案。然后,进行该测量系统的硬件和软件设计,其中硬件部分由电容检测芯片Pcap01接口电路、单片机STM31F103最小系统和供电部分构成,软件部分包括实现电容数字信号采集的C程序设计、Pcap01-AD与单片机的通讯程序和数据处理程序。最后,设计实验平台进行多次试验。试验测试结果表明,在变形镜±50μm的位移区间内,测量灵敏度为200pF/3μm,10nm的位移量对应的电容变化为0.067pF。该系统测量精度高、误差小、检测效率高,能够用于自适应镜面的变形检测,同时也适用于其他微小位移的检测。

A mirror deformation detection system based on STM32 and using the capacitance detection chip Pcap01-AD was designed to solve the problems of small deformation,high change frequency,and difficulty of accurately measuring the microdeformation that were associated with a large aperture adaptive sub-mirror.First,according to the characteristics of the deformable mirror,which was driven by the voice coil motor,a system scheme for measuring the microdeformation of the mirror using the capacitance displacement sensor was proposed.Then,the hardware and software are designed for the measurement system.The hardware was constructed with the microcapacitancedetection chip Pcap01,STM32 F103 microcontroller（MCU）system,and power supply circuit.The software part included programming the lower computer in C language to realize digital signal acquisition of the capacitance,communication between the Pcap01-AD and MCU,data conversion of the upper computer and data processing,real-time display,and data storage.According to the structural characteristics of the large aperture telescope sub-mirror system,the experimental platform was designed to enable the conduction of several tests.The test results show that in the range of 50μm,the measurement sensitivity is 200 pF/3μm,and the system has high accuracy,small error,and high detection efficiency.Thus,this system can be used in adaptive mirror surface deformation detection and other small-displacement measurements.