An Anti-Reflection (AR) coating is a type of optical coating applied to the surface and other optical elements to reduce reflection by vacuum evaporation process. In typical imaging systems, this improved the efficiency since less light is lost due to reflection. In complex system such as telescopes and microscopes the reduction in reflections also improves the contrast of the image by elimination of stray light.
AR produced destructive interference in the beams reflected from the interfaces and constructive interference in the corresponding transmitted beams, which in creases the transmittance of glass or transparent substrates, the transmittance of glass is approximately 91%, with single sided coating the transmittance can increase to 94~95%, if with double sided coating it can increase transmittance up to 98~99%.
(Principle of Anti-Reflection coating)