What are the optical coating characteristics of optical pvd coating machine? Many people are curious. After all, it is a new technology in the vacuum coating industry. It has been widely used in digital technology, traditional silver mirrors, scientific instruments, optical communications, semiconductors, new energy and other industries, and has been recognized by many manufacturers and put into use in large quantities

The main optical film devices of optical pvd coating machine include reflective film, antireflective film, polarizing film, interference filter and spectroscope, etc. They have been widely used in the national economy and national defense construction, and have received increasing attention from scientific and technical workers. For example, the use of antireflection film can reduce the loss of luminous flux of complex optical lenses by ten times; The output power of the laser can be doubled by using mirrors with high reflective film ratio; The efficiency and stability of silicon cells can be improved by using optical films.
The simplest optical film model is a homogeneous dielectric film with smooth and isotropic surface. In this case, the optical properties of optical films can be studied using the interference theory of light. When a beam of monochromatic light plane wave incident on the optical film, multiple reflections and refractions occur on its two surfaces. The directions of reflected light and refracted light are given by the reflection law and refraction law, and the amplitude of reflected light and refracted light is determined by Fresnel formula.
The films of optical vacuum coater can be divided into reflective film, antireflection film/antireflection film, filter, polarizer/polarizer film, compensation film/phase difference plate, alignment film, diffusion film/film, brightening film/prism film/condenser film, black-and-white adhesive, etc. Related derivatives include optical grade protective film, window film, etc.
The characteristics of the optical film of optical pvd coating machine are: the surface is smooth, and the interface between the film layers is geometrically divided; The refractive index of the film can jump at the interface, but it is continuous in the film; It can be a transparent medium or an absorbing medium; It can be normal uniform or normal non-uniform. The practical application of the film is much more complex than the ideal film. This is because: during the preparation, the optical and physical properties of the film deviate from the bulk material, and the starting surface and interface are rough, resulting in diffuse reflection of the beam; Diffusion interface is formed by mutual penetration between film layers; Due to the growth, structure and stress of the film, various anisotropy of the film is formed; The film has complex time effect.
Reflective films can generally be divided into two categories: metal reflective films and all dielectric reflective films. In addition, there is also a metal dielectric reflective film that combines the two to increase the reflectivity of the optical surface.
Generally, metals have large extinction coefficients. When the light beam is incident from the air to the metal surface, the amplitude of the light entering the metal decreases rapidly, so that the light energy entering the metal decreases correspondingly, while the reflected light energy increases. The greater the extinction coefficient, the faster the attenuation of light amplitude, the less light energy entering the metal, and the higher the reflectivity. People always choose the metal with larger extinction coefficient and more stable optical properties as the metal film material. The thin metal material commonly used in the ultraviolet region is aluminum, aluminum and silver are commonly used in the visible region, and gold, silver and copper are commonly used in the infrared region. In addition, chromium and platinum are also often used as film materials for some special films. As aluminum, silver, copper and other materials are easy to oxidize in air and reduce their performance, they must be protected by dielectric films. Common protective film materials include silicon monoxide, magnesium fluoride, silicon dioxide, aluminum oxide, etc.
The advantages of metal reflective film are simple preparation process and wide working wavelength range; The disadvantage is that the light loss is large and the reflectivity cannot be very high. In order to further improve the reflectivity of the metal reflective film, several dielectric layers of a certain thickness can be coated on the outside of the film to form a metal dielectric reflective film. It should be pointed out that the metal dielectric film increases the reflectivity of a certain wavelength (or a certain wave zone), but destroys the neutral reflection characteristics of the metal film.