推导出了离焦量与聚焦误差信号功率的关系式。利用MATLAB软件仿真, 详细分析了像散透镜系统各个参数对离焦量、灵敏度、光斑大小等的影响, 得到了像散圆透镜与像散柱透镜焦距之间的距离关系。结果发现聚焦物镜和探测器参数对最小离焦量、灵敏度、精度有决定性的影响。提出了像散透镜系统各光学参数选择的原则和方法, 并以德国Silicon Sensor公司的QP50-6型四象限探测器为例, 详细分析了离焦量与聚焦误差信号功率的线性关系。这些工作对建立满足应用对象要求的像散法离焦检测系统具有重要的指导意义。

The formula about the relation of the defocus distance and the power of error signal is derived. Utilizing the MATLAB software simulation, the effects of various parameters of the astigmatic lens system on defocus, sensitivity, spot size and so on are analyzed in detail. The relations between the focal length of circular astigmatic lens and cylindrical astigmatic lens are obtained. It is found that the parameters of the focusing lens and the detectors have determining influence on the minimum defocus distance, the sensitivity and the accuracy. The principle and method to choose the various parameters of the astigmatic lens are provided. By the QP50-6 four quadrant detector of the German Silicon Sensor as an example, the linear relationship of the defocus distance and the power of error signal are analyzed in detail. This work has an important guiding significance for establishing the astigmatic method of defocus detection system meeting requirements of the application object.