Optimized Polishing of Conformal Ceramic Windows

The Missile Defense Agency (MDA) has a need to decrease the yield time and increase the through put of optical ceramic conformal windows. Optical manufacturing has been a rapidly growing field with advancements in all technology spectrums. High performance optical systems are needed in aerospace, defense, medical, and commercial components. Industry is requiring these components to be manufactured to tighter tolerances and lower costs. Many advancements have been made in cost reduction and increasing quality in axis-symmetric optics such as flats, spheres, aspheres, and off axis parabolas. Some of the advancements on axis-symmetric parts have been applied to freeform and conformal manufacturing, but, due to the drastic geometric differences, they do not have the same impact in time reduction. Along with the geometric challenges, the materials used for MDA applications are made from hard-to-machine ceramics in order to withstand harsh environments and still provide high quality optical transmission. The harder ceramics require unique methods to remove the proper amount of sub surface damage to meet roughness tolerances. The purpose of this SBIR Phase II proposal is to improve the existing freeform polishing processing methods by 2x to 3x on crystals and hard ceramics. Extensive research has been done to get the current process in a stable condition to consistently produce optical freeform components. This research work was done in prototype phases that have addressed areas that need improvement to reach the optical tolerances, with a focus on quality over production times. New technologies have been created for metrology and machining that specifically address conformal ceramic window challenges. The goal is to move the optical freeform process from small quantity high cost protypes to larger yields and lower cost production. Leveraging the knowledge from research and existing freeform manufacturing processes, new advancements will be made to reach the proposed goal. Five keys areas have been identified to reach the set goal: intelligent machining, fixture improvements, improvements for OptiPro’s OptiSonic technology for ultrasonic grinding, development of deterministic edge polishing, and increased software capabilities in OptiPro’s freeform manufacturing software PROSurf. Improvements in each of these topics will drastically decrease the overall polishing time in conformal window manufacturing. These advancements will have a positive impact on many areas of optical manufacturing as the technology being developed will work on all optical system components to reduce grinding and polishing process times. Approved for Public Release | 23-MDA-11401 (14 Mar 23)