Today, all antireflection coatings are applied using vacuum deposition installations. The housing of the installation is known as box coater, and the lens mount underneath it as the calotte. Up to 130 lenses are placed on the calotte, depending on the size of the coating unit and the lens diameter. As only one side of the lens is coated at a time in the coating process, the lenses have to be turned for coating of the second surface.
Once the lens has been optically finished on both sides, it is cleaned in preparation for the AR coating process. It is routed through several cleaning baths containing different cleaning solutions with ultrasound and temperature support. Even the smallest dirt particles on the lens surface would impair the quality of the coating.
The coating material comes in the form of tablets or granules. During the coating process, small quantities of the coating material which is inserted in ceramic crucibles or water-cooled metal crucibles are heated with the aid of accelerated electrons. This transforms the material from a solid to a gaseous state. The gas molecules leave the surface of the coating material at a speed of approx. 100 m/s and are deposited on the lens. During the vacuum deposition process, the thickness of the coating layer is constantly checked by the use of complex measuring techniques.
To ensure that the AR coating displays the required adhesive strength and hence also the required resistance to abrasion, glass lenses are coated in a hot state, i. e. the lenses are heated to approx. 250 °C during the deposition process.
Such a heat treatment process is not possible for plastic lenses. Plastic lenses in general must not be heated to temperatures over 80 °C, as their dimensional stability and therefore their optical properties would be impaired. For AR coatings on plastic lenses, it is therefore necessary to use coating materials which display good adhesive strength without any need for a tempering process.
The technique for the production of antireflection coatings on lenses which forms the basis of the standard procedures used today was patented by Carl Zeiss in 1936. However, it was not until two decades later that the batch production of AR coatings became possible for spectacle lenses. Until then, AR coatings had been primarily used for binoculars. In 1959 Carl Zeiss was the first manufacturer to offer AR coatings on glass spectacle lenses.