An
optical coating is one or more
thin layers of material deposited on an optical component such as a
lens or
mirror, which alters the way in which the optic
reflects and
transmits light. One type of optical coating is an
antireflection coating, which reduces unwanted reflections from surfaces, and is commonly used on
spectacle and
photographic lenses. Another type is the
high-reflector coating which can be used to produce mirrors which reflect greater than 99.99% of the light which falls on them. More complex optical coatings exhibit high reflection over some range of
wavelengths, and anti-reflection over another range, allowing the production of
dichroic thin-film optical filters.