Anti-Reflection Coatings for Diamond Windows for Extreme Temperatures

Diamond is gaining increasing attention as a potential window material for optical systems set to operate under extremely high temperatures and harsh environmental conditions. This presents a tremendous challenge to develop durable anti-reflection coatings. In this work we report of a Y 2 O 3 based anti-reflection coating on a poly-crystalline chemical vapor deposited diamond window by using ion beam sputtering. We show that under air ambient, the coating is stable up to at least 600°C for several minutes but fails at 750°C. When placed under vacuum, the same coating performs reasonably well even up to 850°C.