大型天文光学镜面在磨镜机上的一种检测方案探讨

One of a method to test a large Astronomical primary mirror on the grinding and polishing machine table

加工大型天文光学镜面时的检验需要占用较大的空间,本文探讨了在焦点以内放置检验装置的方法。通过实时检验镜面,由计算机控制修磨磨盘、自动抛修。

As we know, the accuracy of optical testing is the limit of the accuracy of optical fabrication. For a large optical mirror, usually, we need a vast space for testing at the center of curveture of the concave mirror. For example, we need a tower about 32 meters high for knibe-edge test or interference technique to test an 8 meters f/2 primary mirror. In this paper,we will make an approach to one of an apparatus which consists of an encoder、pentaprism. Sensor. …et al. In above example the tower only less than 16 meters high. A strip plane mirror is placed on the focus of the main mirror. A He-Ne laser beam which perpendicular to the axis of the mirror is passing through the pentaprism and reblect by the mirror to the strip plane. Rotating the plane which links with an encoder untill the beam along the original direction to a sensor. The rotating angle of the plane mirror is twice of the angular aberration. From the angular aberration and the width of zones, we can calculate the shape of the mirror.