Low Cost Finishing of Optical Ceramics

Hard optical ceramics such as aluminum oxynitride (ALON) and spinel are durable materials with excellent transmission properties from the visible to the midwave infrared. These materials have applications as sensor windows and domes as well as transparent armor. One drawback to these materials is the cost of optical finishing which can easily be 1/3 the cost of the finished dome. Significant reductions in the cost of optical finishing these domes could save the Department of Defense millions of dollars in procurement costs. During the Phase I effort, Surmet has identified opportunities for reduction in the cost of finishing ALON domes. Opportunities include near net shape ALON blanks, low cost tooling, and improved generating, grinding, and polishing processes. Deterministic processes for final figure correction may also lower the cost of domes with demanding optical requirements. Initial demonstrations on sub-scale flat and curved surfaces have been completed under the Phase I effort and have demonstrated process time reductions. Additional demonstration tasks are underway. The proposed Phase II effort, will further develop these processes and technologies, culminating in the manufacture of full scale dome prototypes and qualification of the optical and mechanical characteristics of the domes.