Coating is mainly used to reduce reflection。In order to improve the transparency of the lens and the quality of the image，In modern lens manufacturing processes, it is necessary to coat the lens with a coating。The coating of the lens is based on the principle of optical interference，Coat the surface of the lens with a layer of material with a thickness of one-quarter wavelength(Usually fluoride)，Minimize the reflection of light of this wavelength by the lens。obviously，A layer of film only works on one color light，And multi-layer coating can work on multiple colors of light。Multi layer coating usually uses different materials to repeatedly coat the lens surface with film layers of different thicknesses。Multi layer coating can greatly improve the transmittance of lenses，for example，The reflectivity of each surface of an uncoated lens is5%，After single-layer coating, it decreases to2%，And multi-layer coating can reduce0.2%，like this，It can greatly reduce the diffuse reflection between the lenses of the lens，Thereby improving the contrast and sharpness of the image。

When light enters different transmission materials(If air enters the glass)，About5% It will be reflected off，There are many lenses and refractors in optical sights，The entire process can result in a loss of incident light of up to30%to40%。Modern optical lenses are usually coated with a single or multiple layers of anti reflective film made of magnesium fluoride，A single-layer anti reflective film can reduce reflection to 1.5%，Multilayer anti reflective film can reduce reflection to 0.25%，So if the entire scope is appropriately coated，The light transmittance can reach 95%。Lenses coated with a single-layer anti reflective film are usually blue purple or red in color，The lenses coated with multiple layers of anti reflective film appear light green or dark purple 。

Coating is commonly used in camera lenses、short-sighted、hyperopia、Used on corrective glasses such as reading glasses。

Coating is the process of depositing a very thin transparent film on the surface。The purpose is to reduce the reflection of light，Increase light transmittance，抗紫外线并抑低耀光、ghost image;Coatings of different colors，Also makes the color balance of imaging different。in addition，Coating尚可延迟镜片老化、Time of color change。

Common drugs for eyeglass coating:Zirconium dioxide(ZrO₂)、silica(SiO₂)、ITO(Increase lens conductivity and UV resistance)、HT-100(防水膜，Prevent aging and oxidation)……

Coating principle:High voltage electron gun vaporizes the above drugs，Uniformly distributed on the surface of the lens。