为了精确稳定地测量物体微表面形貌, 设计了一种基于改进迈克尔逊结构的空间两步相移干涉系统。该系统在泰曼-格林偏振干涉仪的基础之上, 使用改进的迈克尔逊结构实现分光, 采用偏振方向分别为0°和45°的两偏振片作为相移器件, 在单个CCD相机中同时记录两幅具有90°相移的干涉图像, 然后由离散希尔伯特变换法提取相位, 获取物体表面形貌信息。搭建了两步相移干涉光路, 并通过对玻璃平板表面的检测, 验证了该系统的可行性。结果表明, 在实验室环境下系统重复测量结果的均方根误差小于0.02λ, 在实际微表面测量中具有良好的稳定性。

To measure microsurface profile of an object, a spatial two-step phase-shifting interferometer was proposed based on an improved Michelson architecture. Based on a Tyman-Grean polarization interferometer, the improved Michelson architecture was used as beam-splitting unit, two linear polarizing plates with polarization direction of 0° and 45° were taken as phase-shifting elements. The interferometer can simultaneously capture two interferograms with phase shift of 90° with a single CCD camera. Phases were extracted and surface topography information was obtained by discrete Hilbert transform. A two-step phase-shifting interferometer was set up and glass plate surface was measured to verify the feasibility of this system. In the laboratory environment, the root mean square error of measurement results was less than 0.02λ. The system can be used in measurement of microsurface profile and has good stability.