Thin-film optics

Thin-film optics is the branch of optics which deals with the deposition of one or more thin layers of material onto a substrate (usually glass), most often by an evaporative, chemical or sputtering process such as chemical vapor deposition. These thin films are used to create optical coatings.

The thickness of these layers is typically of the order of 100 nm. They are designed to harness the effects of interference and the difference in refractive index between the layers, the air, and the substrate. These effects alter the way the optic reflects and transmits light. You can observe these effects every day in soap bubbles and oil slicks.

This process is used to create low-emissivity panes of glass for houses and cars, anti-reflective coatings on spectacles, reflective baffles on car headlights, and for high precision optical filters and mirrors.