Optics and optical components are often coated with a fine layer of material in order to modify the light reflected or emitted from them. This material is called an Optical Coating Material, and it is used on everything from bulbs and lenses to mirrors and prisms. The prime uses of Optical Coating Material are to block certain wavelengths of light or to provide a highly reflective surface. In some cases, they provide both functions, reflecting specific wavelengths, while allowing others to pass through unobstructed.
Camera lenses and vanity mirrors both provide a common example of Optical Coating Materials at work. Camera lenses use a dielectric coating that provides an anti-reflection coating. These coatings consist of magnesium fluoride, calcium fluoride, or similar materials. They allow the user to select the specific texture of the light entering the camera. For instance, dielectric coating can reduce glare or enhance certain colors (wavelengths) by obstructing others. Mirrors utilize a reflective coating, typically a polished, ultra-thin layer of metal. The materials of choice are silver and aluminum because they provide high levels of reflectivity. In the case of silver, the coating is often achieved by the deposit of a silver vapor. High-reflector coatings can reflect more than 99 percent of the light aim at them. But even the more expensive silver coatings have limited reflectivity with certain wavelengths, which results in a modified color to the reflection.
Optical Coating Materials find many additional uses, as well, and are not simply used in household items. Beam splitters, lasers and optical cables all make use of Optical Coating Materials. In thin-film optical features, Optical Coating Materials serve to magnify some wavelengths and negating others. The effectiveness of the coating is affected by the angle of the entering light, a factor that plays an important role in beam splitters.
Precision manufacturers provide a wide range of Optical Coating Materials, including nickel, silver, aluminum, gold, copper and titanium mirror coatings, as well as single and multi-layer anti-reflection coatings. These can be custom designed for any application, from decorative to high-precision photonics. Other uses include thermal foil and infrared protection.