An AR coating is a technology that reduces reflection and improves light transmittance by applying multiple layers of optical film on the surface of a lens. The principle of AR coating is to reduce the phase difference between the reflected light and the transmitted light by controlling the thickness and refractive index of different layers of films.
AR (Anti-Reflective) coatings consist of multiple layers of optical films, each of which has a specific function and characteristic. This article provides a detailed explanation of the materials, layer numbers, and roles of each layer in the AR coating.
Materials:
The main materials used in AR coatings are metal oxides and silicon dioxide. Aluminum oxide and titanium oxide are commonly used as metal oxides, and silicon dioxide is used to adjust the refractive index of the film.
Layer Numbers: The layer numbers of AR coatings are generally 5-7, and different designs can have different layer numbers. In general, more layers result in better optical performance, but the difficulty of coating preparation also increases.
Roles of Each Layer:
(1) Substrate layer: The substrate layer is the bottom layer of the AR coating, which mainly enhances the adhesion of the substrate material and protects the lens from corrosion and pollution.
(2) High refractive index layer: The high refractive index layer is the thickest layer in the AR coating and is usually composed of titanium oxide and aluminum oxide. Its function is to reduce the phase difference of reflected light and increase the light transmittance.
(3) Low refractive index layer: The low refractive index layer is generally composed of silicon dioxide, and its refractive index is lower than that of the high refractive index layer. It can reduce the phase difference between reflected light and transmitted light, thereby reducing the loss of reflected light.
(4) Anti-pollution layer: The anti-pollution layer enhances the wear resistance and anti-pollution properties of the coating, thereby prolonging the service life of the AR coating.
(5) Protective layer: The protective layer is the outermost layer of the AR coating, which mainly protects the coating from scratches, wear, and pollution.
Color
The color of the AR coating is achieved by adjusting the thickness and material of the layers. Different colors correspond to different functions. For example, blue AR coating can improve visual clarity and reduce glare, yellow AR coating can enhance contrast and reduce eye fatigue, and green AR coating can reduce glare and enhance color vibrancy.
In summary, the different layers of the AR coating have different functions and work together to reduce reflection and increase light transmittance.
The design of AR coatings needs to consider different application environments and requirements to achieve the best optical performance..
Post time: Feb-21-2023