Preparation of Uniform SiO2 Films on Sapphire Dome by r.f. Magnetron Reactive Sputtering

Abstract

The convex surface of the infrared dome is exposed to the harsh environment of the outside world, and therefore requires a coating which not only increases transmission but is able to withstand rain erosion so as to enhance system performance. This paper deals with the techniques that were developed to deposit a uniform thick SiO2 coating for sapphire dome by radio frequency magnetron sputtering. Results show that average transmission increment in wavelength range from 3 to 5um for the sapphire dome coated on convex surface was more than 4.0%. The transmission non-uniformity over the convex surface of the coated sapphire dome was less than 1.7%.