Practically every child has heard this question that Snow White's stepmother asked her magic mirror. Even though mirrors can perform magic only in fairy tales, they definitely have something magic about them: a thin layer of material is applied to glass and, abracadabra, we can see our own reflection!
The idea to apply an additional layer to a glass surface and therefore improve its optical properties led to the founding of a special field of optics. Thin optical layers determine whether light is transmitted or reflected. As a key technology, they are a key component of any optical system and can be found practically everywhere in our daily lives. On eyeglass lenses, in particular, they ensure that the wearer enjoys clear vision without reflections or prevent ultraviolet radiation from entering the eye. Even the rescue blanket in first aid kits is based on thin layer technology. Scientists also use these thin layers in modern microscopes or in large telescopes.
ZEISS played a pivotal role in the ongoing enhancement of thin layer optics: in 1935 ZEISS scientists in Jena developed the "T-coating." To this very day this is used to reduce irritating reflections and increase transmission on optical glass surfaces. To apply the layer, the desired material is first vaporized. It subsequently condenses on the substrate and forms a solid layer in the range of micro to nanometers. These thin layers determine the physical properties and fields of application of the coated material.