Optical thin film is a coating that is added to glass or clear plastic lenses. Once it has been applied, the optical thin film changes the nature of light that passes through the lens by refracting or reflecting certain wavelengths. The properties of the thin film can alter the properties of either a short range of wavelengths or a large range, depending on the properties of the film. The process of creating this type of thin film is highly technical and must be done in a special lab.
One way to apply an optical thin film to a lens is through reactive sputtering. In this process, molecules of the thin film material are electrically charged inside a vacuum chamber and eventually settle on the lens. In chemical vapor deposition, however, vaporized molecules of the optical thin film material bind to other molecules that are chemically attracted to the material of the lens.
Optical thin films can be used in a number of different ways. The coating on a lens can be designed to interfere with and cancel out certain wavelengths of light. This effectively blocks these colors from passing through the filter. The thin film can be designed to amplify certain wavelengths as well. It is also possible for optical thin film to be designed to work within a narrow or wide range of light wavelengths from the infra-red through the ultraviolet range.
Many optical devices use more than one optical thin film at a time. They can be deposited on top of one another on the same piece of substrate. The application of several of these films to the same lens allows the device to modify what is seen through the lens in several ways at once.
A number of industries use optical thin films. Optical coatings can be used on air and spacecraft, for instance. They are often designed to keep harmful wavelengths of light from passing through the glass on a plane or spacecraft and to add strength to these surfaces. Optical thin film can also be used for telescope, microscope, and camera lenses, where they often serve as filters.