基于位置敏感探测器的微位移测量关键电路设计

Design on the key measurement circuit for small displacement measurement system with position sensitive detector

位置敏感探测器PSD(Position Sensitive Detector PSD)具有位置分辨精度高(可达1～2μm)、输出实时性好(响应时间约几微秒)、系统简洁的特点,在位置探测及相关领域内获得了广泛的应用;但PSD的输出信号小,易受到电路噪声的影响,若要充分发挥其性能,则需要高精度、高稳定度、低噪声的测量电路。针对PSD这种较高的使用要求,通过对其等效模型的分析,找到了影响位置分辨精度的主要因素,并提出了一种新形式的测量电路,减少了测量电路级数,降低了电路的噪声以及测量电路内部的漂移,同时具有对位置测量非线性的校正功能。采用上述原理以S1880PSD建立的位置测量系统的位置分辨达到2～3μm。

Position sensitive detectors have been widely applied in the field of displacement measurement and relative field for its good characteristics such as high position resolution （1-2 μm）,high speed response （ - μs）,simplified system. The output current signal from a PSD is very small and contain noise. A low noise measurement circuit with a high precision and stability must be adopted in order to obtain the best performance. The main factor determining position resolution is discovered by analyzing the equivalent noise model of the measurement principle circuit . One kind of measurement circuit with low noise and good stability is developed . It features a few circuit stages and application of microprocessor. The non-linear error and inner offset or shift can be removed easily . The position displacement measurement system with PSD S1880 developed achieves position resolution of 2-3 μm.