Optical coating machine
Optical coating machine refers to the process of coating a layer (or multiple layers) of metal (or dielectric) film on the surface of optical parts. The purpose of the surface coating of optical parts is to reduce or increase the requirements for light reflection, beam splitting, color separation, filtering, and polarization. Common coating methods are vacuum coating (a physical coating) and chemical coating. The purpose of the coating is to change the reflection and transmission characteristics of the surface of the material.
Optical coating machine in the visible and infrared bands, the reflectance of most metals can reach 78% to 98%, but not higher than 98%. Whether using copper, molybdenum, silicon, germanium as a mirror, or germanium, gallium arsenide, zinc selenide as the output window and transmission optical element material, or ordinary optical glass as the mirror, output mirror, and transmission optical element material , Can not meet the requirements. Because the output mirror has different transmittance requirements in different applications, an optical coating method is needed. For the infrared band of CO2 laser lamps, the commonly used coating materials are yttrium fluoride, hafnium fluoride, germanium, etc .; For the near infrared band or visible light band of YAG laser lamps, the commonly used coating materials are zinc sulfide, magnesium fluoride, Titanium dioxide, zirconia. Wait. In addition to the high-reflection film and the anti-reflection film, a different film can be coated to enhance the reflection at one wavelength and the transmission at another wavelength, such as the spectral film in laser frequency doubling technology. Application of light interference in thin film optics. A common method of optical thin film technology is vacuum sputtering coating on a glass substrate, which is generally used to control the reflectance and transmittance of the incident beam of the substrate to meet different needs. In order to eliminate the reflection loss on the surface of the optical element and improve the imaging quality, the surface of the optical element is coated with one or more transparent dielectric films, which is called an antireflection film. With the development of laser technology, different requirements for the reflectance and transmittance of thin films have been promoted, which has led to the development of multilayer high-reflection films and broadband anti-reflection films. In many applications, polarized reflective films, color spectrum films, cold light films, and interference filters are made from highly reflective films.
After the optical coating machine coats the surface of optical parts, light is reflected and transmitted multiple times on the thin film layer, forming multi-beam interference.Controlling the refractive index and thickness of the film can obtain different light intensity distributions, which is the basic principle of interference coating. The optical film is realized in a high-vacuum coating cavity. The traditional coating process requires increasing the substrate temperature (usually around 300 ° C), and processes such as ion assisted deposition (IAD) can be performed at room temperature.