High-Energy Laser Coatings for Large, Lightweight, and Compliant Deployable Space Optics

The purpose of this Phase-II effort is to develop filtered cathodic arc plasma deposition (FCAPD) for applying multi-layer, highly reflective optical coatings to extremely light-weight and large membrane mirrors for space and high-altitude-based high-energy laser applications where glass mirrors are not practical. FCAPD coatings are ideal for this application because the deposition ions have higher energy and thus produce denser films with fewer voids that are less susceptible to changes in environmental conditions and have better adhesion than films produced using other methods. In addition, the intrinsic film stress of FCAPD films can be controlled during deposition, which is critical to controlling the shape of the membrane mirror. To maximize the probability of success, a step-wise approach will be used where the FCAPD process will first be developed on coupon-sized membrane substrates to achieve film thickness and stress control. Once this is achieved, the process will be scaled-up to a ~10 cm diameter membrane mirror and then to an actual 0.25 m diameter prototype. Theoretical calculations will also be performed to determine the effect of substrate heating and radiation pressure on the shape and performance of the mirror system.