Large mirror lightweight method based on temperature control strategy

Abstract

Large optical mirror is a direct and effective way to improving relevant optic system resolution. However, along with mirror size improving, mirror weight increases as exponentially. So mirror lightweight is the key technology for large optical mirror. Moreover as optical surface size increasing, it is hard to control temperature gradient on mirror surface. So analyzing mirror lightweight method, in view of temperature grade distribution on mirror reflecting surface, is more advantage for large mirror application practically. Starting from a large SiO2 primary mirror, the papers introduce temperature analysissitus and mechanics analysissitus to discuss large mirror lighting weight method in view of mirror excellence surface shape quality, regarding temperature gradient distribution on mirror reflecting surface as state function, minimizing mirror weight as object function, Zernike polynomial coefficient as describing optical aberration distribution on mirror surface. From the analysis results, with regard to classic lighting form, papers set up composite radiate lighting form, which is propitious to temperature transferring, improves mirror surface mechanical stiffness and reduces mirror effectual surface density in addition. Appling the lighting form, the lighting rate is less than 70 percent, and the PV value less than λ/5(λ=632.8nm), RMS of mirror surface shape less than λ/20, temperature gradient under 0.001k/mm. From analysis results, it can conclude that this lighting method in view of controlling mirror temperature distribution can reduce large mirror effectual surface density, and control temperature distribution effectively, which promotes large mirror surface temperature controlling technology and supplies technique support to extend large mirror application space.