Matched and Ultra-Low CTE Optical Materials

A new material and processing technology has been developed and demonstrated that will dramatically reduce the cost of manufacturing and refurbishing large aluminum based mirrors for optical test applications. Such precision mirrors are also required for surveillance, directed energy, cryo-vacuum scene generation, optical testing, and DoD-sponsored space programs. Traditional aluminum mirror technology is used cryogenic chambers for reasons of thermal expansion matching between the optical bench, mounts and components. These mirrors have to be electroplated with nickel, polished and then reflective coated. This process leads to strain mismatches during the chamber cool down resulting in optical deformation in the mirror and de-lamination of the surfaces after repeated thermal cycles. The Phase I polymer coating process was developed with tuned thermal expansion materials to encourage the membrane to bond tenaciously to the substrate and to act as a strain buffer layer between the coating and optic substrate. The air side of the polymer casting creates a highly polished specular surface for the mirror with nearly a factor of 10:1 improvement — eliminating the need for costly final polishing.