Papers by Author: Shenq Tsong Chang

Abstract: Optomechanical analysis and design approaches for development of large mirror mount are presented in this article. The relationship between mirror optical aberration and gravity effect is studied for difference mirror mount designs. A detailed structural analysis of mirror mount design using finite element model combined with Zernike polynomials fitting is found successfully to predict optical aberration in the Cassegrain optical system.

Abstract: Radius of curvature is one of the key parameters of optical components. A variety of methods have been developed for this measurement. This paper describes a novel way, named “CMM spherometry by probe compensation”, to measure the radius of curvature of optical surfaces by coordinate measuring machine (CMM). The measurement combines CMM measurement and iteration calculation scheme is presented. The measurement results of CMM and the trace samples are compared. The effect of temperature compensation is discussed.

Abstract: This article reports an approach of light-weighted mirror design and analysis to increase the weight reduction ratio and improve optical performance based on the finite element method and opto-mechanical analysis. The approach is to represent mirror surface deformation derived from finite element analysis (FEA) by Zernike polynomials, such that the impact of deformation on optical system performance can be evaluated by the optical design and analysis program. The experimental modal analysis was also performed to validate the FEA results. The numerical result shows that the light-weighted primary mirror of Cassegrain telescope is obtained by this approach and predicted deformation fulfills the requirements of optical design.

Abstract: This article reports an accurate analysis approach of finite element modeling and optical modeling. It has been used for design and analysis of many opto-mechanical systems such as large telescopes and laser systems. The approach is to represent mirror surface deformation derived from finite element analysis (FEA) by Zernike polynomials, such that the impact of deformation on optical system performance can be evaluated by optical design and analysis program. The methodology of shell-based and solid-based finite element modeling and the comparison of their results have been described in this paper. The result shows that the deformation of the light-weighted mirror designed by this approach fulfills the requirements of optical design. The simulation results of shell based FE model are in good agreement with those of solid based FE model.