The main optical thin film devices include reflective films, antireflection films, polarizing films, interference filters, and beamsplitters. They have been widely used in the national economy and national defense construction, and have received increasing attention from scientists and technicians. For example, the use of an anti-reflection film can reduce the luminous flux loss of a complex optical lens by a factor of ten; the use of a mirror with a high reflectance can double the output power of the laser; and the use of an optical film can improve the efficiency and stability of the silicon photocell. Sex.

 
The simplest optical film model is a thin layer of uniform medium with a smooth, isotropic surface. In this case, the optical properties of the optical film can be studied using the interference theory of light. When a bundle of monochromatic plane waves is incident on the optical film, multiple reflections and refractions occur on its two surfaces. The direction of the reflected and refracted light is given by the law of reflection and the law of refraction. The amplitude of the reflected and refracted light The size is determined by the Fresnel formula (see the refraction and reflection of light at the interface).
 
The characteristics of the optical film are: the surface is smooth, the interface between the layers is geometrically divided; the refractive index of the film layer can change at the interface, but it is continuous in the film layer; it can be a transparent medium or an absorption Medium; can be normal or uniform. The actual application of the film is much more complicated than the ideal film. This is because: when prepared, the optical properties and physical properties of the film deviate from the bulk material, and the surface and interface are rough, resulting in diffuse scattering of the light beam; interpenetration between the film layers forms a diffusion interface; due to the growth of the film layer , structure, stress and other reasons, the anisotropy of the film is formed; the film layer has a complex time effect.
 
◆ The application of optical film is everywhere, from glasses coating to mobile phone, computer, TV LCD display to LED lighting, etc. It is full of all aspects of our lives and makes our life more colorful.
 
◆ The definition of optical film is: a thin and uniform dielectric film layer attached to the surface of the optical device during the propagation path, which is characterized by reflection, transflection and polarization when the dielectric layer is layered. It is used to achieve all the special forms of light, such as the total transmission of light in one or more bands, or the total reflection of light or the polarization separation of light.
 
◆ Optical films can be divided into “geometric optics and physical optics”. Geometry optics are geometric dielectric layers formed through the surface of optical devices to change the path of light to achieve beam adjustment or redistribution. Physical optics is the natural world. The unique optical material elements are nano-treated to the dielectric film layer formed on the surface of the desired optical device, and the characteristics of the optical material elements transmitted through the dielectric film layer are enhanced to change the functions of light polarization, transmission, reflection and the like.
 
◆ Generally, the preparation conditions of optical films are required to be high and precise. The optical film is prepared by dry preparation and wet preparation. The dry preparation method (including vacuum coating: evaporation, magnetron sputtering, ion plating, etc.) is generally used for physics. The preparation of optical films, wet preparation methods (including coating methods, casting methods, thermoplastic methods, etc.) are generally used for the preparation of geometric optical films.