计算机再现全息与辅助球面混合补偿检测凸非球面方法研究

Hybrid Compensation Testing of Convex Asphere with Computer Generated Holograms and Fold Sphere

大口径凸非球面镜在现代光学系统的应用日渐广泛,尤其在离轴三反光学系统中,它往往作为次镜使用。出于力学特性和热学特性考虑,一般采用不透明的Si C材料来制作此类非球面镜面,而且对于离轴系统,次镜的全口径均参与成像。口径大、加工材料不透明且无中心遮拦,使得传统的检测方法已经无法实现对此类非球面的检测。为解决此问题,提出一种计算机再现全息(CGH)与辅助球面镜混合补偿的凸非球面检测方法,构建了基于CGH辅助功能区域的检测对准方案,并以此方法对一口径为φ120 mm的Si C凸非球面反射镜进行了混合补偿检测,其检测结果与子孔径拼接检测结果在均方根(RMS)值为1/50λ精度下一致,验证了该方法的可行性与正确性。

Large convex aspheric mirrors are widely used in optical system, especially for off-axis three mirror systems as secondary mirrors. Considering the mechanical and thermal properties, SiC is chosen as the material of the mirror, which is opaque. For off-axis optical system, the full aperture of the secondary mirror is used for imaging. Because of the properties of large convex aphereric mirrors, such as large aperture, opacification and no obstruction in the optical system, testing of this kind of asphric mirrors can＇t be accomplished with traditional method. To solve the testing problem, hybrid compensation testing method with computer-generated hologram （CGH） and fold sphere is proposed, and an alignment method based on the assistant areas of CGH is proposed too. With actual project, a φ 120 mm mirror is tested using hybrid compensation testing method. The testing result is the same with the stitching testing result at 1/50 2 root mean square （RMS）, which proves the feasibility and validity of the hybrid compensation testing method.