The optical film coated by the optical pvd coating machine can be divided into: reflective film, anti-reflection film/anti-reflection film, optical filter, polarizer/polarizing film, compensation film/retardation plate, alignment film according to its use classification, characteristics and application , diffuser film/sheet, brightness enhancement film/prism sheet/condenser sheet, shading film/black and white glue, etc. The related derivatives are optical grade protective film, window film and so on.

1. Reflective film
       Reflective films can generally be divided into two categories, one is a metal reflective film, and the other is an all-dielectric reflective film. In addition, there are metal-dielectric reflective films that combine the two, the function of which is to increase the reflectivity of the optical surface. Generally, metals have large extinction coefficients. When the light beam is incident on the metal surface from the air, the amplitude of the light entering the metal is rapidly attenuated, so that the light energy entering the metal decreases correspondingly, while the reflected light energy increases. The larger the extinction coefficient is, the faster the light amplitude decays, the less light energy enters the metal, and the higher the reflectivity. People always choose metals with larger extinction coefficient and more stable optical properties as metal film materials. The commonly used metal thin materials in the ultraviolet region are aluminum, aluminum and silver are commonly used in the visible light region, and gold, silver and copper are commonly used in the infrared region. In addition, chromium and platinum are often used as film materials for some special thin films. Since materials such as aluminum, silver, and copper are easily oxidized in the air and reduce their performance, they must be protected with a dielectric film. Commonly used protective film materials are silicon monoxide, magnesium fluoride, silicon dioxide, aluminum oxide, and the like.
 
         The advantage of the reflective film is that the preparation process is simple and the working wavelength range is wide; 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 with a certain thickness can be added to the outside of the film to form a metal-dielectric reflective film. It should be pointed out that the metal dielectric reflective film increases the reflectivity of a certain wavelength (or a certain wavelength region), but destroys the characteristics of neutral reflection of the metal film.
 
        All-dielectric reflective coatings are based on multi-beam interference. Contrary to anti-reflection coatings, coating the optical surface with a film with a higher refractive index than the base material increases the reflectivity of the optical surface. The simplest multi-layer reflection is formed by alternating evaporation of high and low refractive index materials, and the optical thickness of each layer is one-quarter of a certain wavelength. Under this condition, the reflected light vector on each plane participating in the superposition has the same vibration direction. The synthetic amplitude increases with the number of film layers.
 
        Aluminum foil reflective film Dike aluminum foil thermal insulation coil, also known as barrier film, thermal insulation film, thermal insulation foil, heat extraction film, reflective film, etc. It is made of aluminum foil veneer + polyethylene film + fiber braid + metal coating film laminated by hot melt adhesive. The solar absorption rate (solar radiation absorption coefficient) of the aluminum foil thermal insulation coil is extremely low (0.07), and it has excellent thermal insulation performance, which can reflect more than 93% of the radiant heat, and is widely used in building roofs and external walls. Keep warm. Correspondingly, it is an anti-reflection film, the main function is to improve the diffraction of light, so that people can watch text and graphics for a long time. This requires an anti-reflection film with a smooth surface and less reflection.
 
2. Anti-reflection coating / anti-reflection coating
        Anti-reflection coating, also known as anti-reflection coating, its main function is to reduce or eliminate the reflected light of lenses, prisms, plane mirrors and other optical surfaces, thereby increasing the light transmission of these components and reducing or eliminating stray light in the system. Antireflection coatings are based on the wave nature and interference phenomena of light. If the two light waves with the same amplitude and the same wavelength are superimposed, the amplitude of the light waves will increase; if the two light waves have the same origin and the wave paths are different, if the two light waves are superimposed, they will cancel each other out. The anti-reflection film uses this principle to coat the surface of the lens with an anti-reflection film (AR-coating), so that the reflected light generated on the front and rear surfaces of the film interferes with each other, thereby offsetting the reflected light and achieving the effect of anti-reflection. The simplest AR coatings are monolayers. In general, it is difficult to achieve the ideal anti-reflection effect with a single-layer anti-reflection coating. In order to achieve zero reflection at a single wavelength, or to achieve a good anti-reflection effect in a wider spectral region, double-layer, three-layer or even more Anti-reflection coating with multiple layers.
The practical application of anti-reflection film is very wide, the most common are lenses and solar cells - by preparing anti-reflection film to improve the power watt value of photovoltaic modules. At present, the anti-reflection film material used in crystalline silicon photovoltaic cells is silicon nitride. Using plasma enhanced chemical vapor deposition technology, ammonia and silane are ionized and deposited on the surface of silicon wafers. Better anti-reflection effect. Early photovoltaic cells used silicon dioxide and titanium dioxide films as antireflection layers.
 
3. Filter
     The filter is made of plastic or glass and added with special dyes. The red filter can only pass red light, and so on. The refractive index of the glass sheet was originally similar to that of air, and all colored lights could pass through, so it was transparent, but after dyeing, the molecular structure changed, the refractive index also changed, and the passage of some colored lights changed. For example, when a beam of white light passes through a blue filter, a beam of blue light is emitted, while very little green and red light is emitted, and most of it is absorbed by the filter.
 Filter products are mainly classified by spectral band, spectral characteristics, film material, application characteristics, etc. Spectral band: UV filter, visible filter, infrared filter; spectral characteristics: bandpass filter, cut-off filter, spectral filter, neutral density filter, reflection filter; film Layer material: soft film filter, hard film filter. The hard-coated filter not only refers to the hardness of the film, but also its laser damage threshold, so it is widely used in laser systems. Soft film filters are mainly used in biochemical analyzers. Bandpass type: Light in the selected band passes, and light outside the passband is cut off. Short-wavepass type (also called low-pass): Light shorter than the selected wavelength passes through, and light longer than the wavelength is cut off. Such as infrared cut filter, IBG-650. Long-wavepass type (also called high-pass): light longer than the selected wavelength passes through, and light shorter than the wavelength is cut off, such as infrared transmission filter, IPG-800. Color filter is an important part of TFT-LCD backlight module. Color filter is an important part of TFT-LCD backlight module.
 
4. Polarizer
        The full name of polarizing film (PolarizingFilm) should be polarizing film. Liquid crystal display imaging must rely on polarized light. The main function of the polarizer is to turn the natural light without polarization into polarized light, and convert it into polarized light. With the twisting characteristics of liquid crystal molecules, it can control the passage of light or not, thereby improving the light transmittance and viewing angle range. Anti-glare and other functions.
Polarizers can be widely used in modern liquid crystal display products: LCD TVs, notebook computers, mobile phones, PDAs, electronic dictionaries, MP3, instruments, projectors, etc., and can also be used in fashion polarized glasses. Among them, the application of LCD is the main force driving the development of the polarizer industry.
 
5. Compensation film / retardation plate
        The compensation principle of the compensation film is to correct the phase difference generated by the liquid crystal at each viewing angle under various display modes (TN/STN/TFT (VA/IPS/OCB)), in short, to make the birefringence of the liquid crystal molecules Properties are compensated by symmetry. To distinguish from their functional purposes, they can be slightly divided into retardation films, chromatic aberration compensation films, and viewing angle expansion films that simply change the phase. The compensation film can reduce the amount of light leakage of the liquid crystal display in the dark state, and can greatly improve the contrast and chromaticity of the image within a certain viewing angle and overcome the problem of partial gray scale inversion.
 
        The above are five types of optical films coated by optical pvd coating machines. Generally, friends who do not know about optical coating should have little knowledge of this aspect. Today, I will popularize this knowledge for everyone, hoping to help everyone.