Thorium-free interference coatings for infrared applications

This paper discusses improvements in manufacturing of coated infrared optical components. Such components often have key functions in defence, security or space applications and must withstand severe environmental conditions. Therefore, very durable coatings are desired. As a consequence of its radioactivity the formerly used low refractive index material thorium fluoride is substituted. Examples for beam splitter cubes contacted with novel infrared transparent cement, interference filters, mirrors and AR coatings are presented.