Some effects of aerospace thermal environments on high-acuity optical systems.

The effects of the major features of an aerospace thermal environment on the principal components of large-aperture photographic catadioptric systems are considered. First approximation solutions to the focal shift and on-axis wavefront aberration produced by heat fluxes in windows (or corrector plates) are presented. The effects of axial heat fluxes and uniform temperature changes on mirror structures representative of current practice in lightweight-mirror technology are examined, and first approximations to the deformations of simple slab mirrors, Kanigen-coated metal mirrors, and sandwich-plate construction are derived. Some conclusions on the comparative utility of Kanigen-coated beryllium mirrors and solid or egg-crate fused-silica mirrors are drawn.