1 October 1990 Evaluation of mirror thermal distortions from temperature measurements
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Abstract
A method is described to assess the figure change created by thermal distortion in beryllium sandwich mirrors during solar exposure in space. A NASTRAN finite element model of a mirror is used to evaluate the procedure, which uses embedded temperature sensors. The method is tested, with respect to six parameters, on an aluminum thermal surrogate mirror. Thermal gradients in most full-depth sandwich configurations are shown to be minimized, due to the high thermal conductivity of aluminum. Overall rms figure and defocus deformation are predicted to within 15 percent; the coma and astigmatism are predicted to within 20-25 percent; and the variability in predicting higher order distortions is wide. Defocus is shown to be the most likely dominant term in temperature-induced distortion. The notion is posited that provisions are necessary to counterbalance the high CTE of metal mirrors during solar exposure.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Steven E. Forman, Steven E. Forman, John A. Sultana, John A. Sultana, } "Evaluation of mirror thermal distortions from temperature measurements", Proc. SPIE 1303, Advances in Optical Structure Systems, (1 October 1990); doi: 10.1117/12.21540; https://doi.org/10.1117/12.21540
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