光学学报, 2011, 31 (4): 0422001, 网络出版: 2011-03-30
用正弦光栅的朗奇法检验大口径非球面面形
Large-Aperture Aspheric Surfaces Testing by Using Sinusoidal Grating Based on Ronchi Method
光学测量 三维面形测量 朗奇检验法 非球面镜 四步相移 optical measurement three-dimentional shape measurement Ronchi test aspheric mirror four-step phase-shifting
摘要
基于朗奇(Ronchi)检验法和同步相位探测技术,在点光源离轴情况下提出一种检验非球面反射镜的方法。该方法利用透射液晶显示器(LCD)显示垂直和水平两个方向的正弦光栅,由摄像机记录经被测镜面反射产生的光栅变形条纹图,通过四步相移法获得条纹图的相位分布。由变形条纹和光栅的同名相位点确定被测镜面每一点的横向像差,对应理想镜面的横向像差由几何关系算出,通过两镜面对应点的横向像差之差获得待测点面形偏差的梯度信息,对其积分恢复面形偏差,最后重建被测面形。检测中光栅由计算机产生,可实现精确的相移,使垂直和水平光栅严格达到90°。采用预设标记点来引导相位展开,有效地解决了变形条纹和光栅的相位对应问题。模拟和实验初步验证了这一方法的可行性。
Abstract
A method based on Ronchi test and synchronous phase detection technology is presented to measure the aspheric mirror, where the point source is located beside the axis of the surface. A liquid crystal display screen displays the vertical and horizontal sinusoidal gratings and a camera captures the deformed fringe patterns generated by the reflection of the mirror. By four-step phase-shifting technique, the phase distributions are obtained. According to points with the same phase on the deformed fringes and grating, the transverse aberration of all tested points can be calculated, while that of the relevant ideal mirror can be worked out by geometry algorithms. Then the residual transverse aberration can be taken and thus the gradient of shape deviation can be determined. Tested mirror can be reconstructed after restoring shape deviations by integral processing. In experiment, the computer-generated fringe will bring a no-error phase shift and control the angle of two gratings to be 90°. A marked point is used to guide the phase unwrapping procedure. Computer simulations and preliminary experiment validate the feasibility of this method.
郭春凤, 苏显渝, 窦蕴甫, 陈文静, 雷柏平, 伍凡. 用正弦光栅的朗奇法检验大口径非球面面形[J]. 光学学报, 2011, 31(4): 0422001. Guo Chunfeng, Su Xianyu, Dou Yunfu, Chen Wenjing, Lei Baiping, Wu Fan. Large-Aperture Aspheric Surfaces Testing by Using Sinusoidal Grating Based on Ronchi Method[J]. Acta Optica Sinica, 2011, 31(4): 0422001.