At present, there are more than 60 common varieties of optical coating materials, and their varieties and application functions are still being developed. In recent years, it has developed a metal film system. When the thickness of gold, silver, copper and aluminum is 7-20um, the transmittance of visible light is 50%, and the transmittance of infrared light is less than 10%. This kind of coating has been successfully The panel used in the Apollo spacecraft is used to transmit part of the visible light and reflect almost all of the infrared light for thermal control. The following article mainly introduces the characteristics and classification of optical coatings.
It is composed of plated layered media and spreads light beams through the interface. The application of optical coatings began in the 1930s. Optical coatings have been widely used in the fields of optics and optoelectronics to manufacture various optical instruments. The preparation requirements are high and precise.
The definition of optical coating is: refers to the uniform thickness of the dielectric film attached to the surface of the optical device during the propagation path of light, and the reflection, transmission (refraction) and polarization characteristics when passing through the layered dielectric film. To achieve the special forms of light we want, such as all transmission of light in one or more bands, or all reflection of light, or polarization separation.
An optical coating is ubiquitous in our lives, from precision and optical equipment, display equipment to optical coating applications in daily life; for example, glasses, digital cameras, various household appliances that we usually wear, or anti-counterfeiting on banknotes Technology can be called an extension of the application of optical coating technology. If there is no optical coating technology as the basis for development, modern optoelectronics, communications or laser technology will not be able to make progress, which also shows the importance of optical coating technology research and development.
Optical coating refers to the preparation or coating of one or more dielectric films or metal films or a combination of these two types of films on optical components or independent substrates to change the transmission characteristics of light waves, including light transmission, Reflection, absorption, scattering, polarization and phase change. Therefore, through proper design, the transmittance and reflectance of the surface of different waveband components can be adjusted, and the light of different polarization planes can also have different characteristics.
Generally speaking, the production methods of optical coatings are mainly divided into dry and wet production processes. The so-called dry method means that no liquid appears in the entire processing process. For example, vacuum evaporation is in a vacuum environment, where the solid raw material is heated with electric energy, after being sublimated into a gas, it is attached to the surface of a solid substrate to complete the coating. Processing. The golden, silver or metallic packaging film used for decoration in daily life is the product manufactured by dry coating. However, in consideration of actual mass production, the application range of dry coating is smaller than that of wet coating. The general method of wet coating is to mix ingredients with various functions into liquid coatings, coat them on the substrate in different processing methods, and then dry and solidify the liquid coatings to make products.