Coatings

摘要

A scratch resistant coating (44) for the window (42) of an infra red sensor comprises a layer of zirconium oxynitride or hafnium oxynitride. The formula of the coating is M1-(y-z) Oy Nz where y and z are both in the range 0.1 to 0.4. The coating (44) and the window (42) are both transmissive in the infra red and visible ranges of the spectrum.