The Thin Mirror Deformation and Stress Distribution Analysis Based on Different Influence Functions

摘要

The active support technique can be applied in the fabrication of large thin meniscus mirror. It can reduce the grinding and polishing difficulty for thin mirror. Compare between two kinds of influence function, we correct the Zernike 5th, 6th, 10th and 11th mode deformation. The low-order Zernike modes which are prone to appearing during large primary mirror processing are revised with active support technology. Influence functions are expressed with Z coordinate value and Zernike coefficient of surface shape. This paper reports that respectively adopting different influence functions to solve correction forces and the correction forces compensates specific Zernike modes of mirror deformation. After comparing the PV and RMS values of amendatory residual of surface shape, we analyze the effect of different correction forces to the biggest stress on the underside of the primary mirror. We compare the two methods based on the PV and RMS values of the residual error and the Max-stress. Gain a conclusion that correction forces obtained from Z coordinate value of surface shape is superior to the one obtained from the Zernike coefficient of surface shape.