Magnesium fluoride coating: multi-field applications and excellent performance

The main purpose of coating is to reduce reflections and to improve the transmittance of the lens and the quality of the image. In modern lens manufacturing processes, the lens must be coated. Lens coating is based on the principle of optical interference. A layer of substance (usually fluoride) with a thickness of one-quarter wavelength is coated on the surface of the lens to minimize the reflection of the lens to the color light of this wavelength.

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• One layer of film only works on one color light, while multi-layer coating can work on multiple colors of light. Multi-layer coating usually uses different materials to repeatedly coat different thicknesses of film layers on the surface of the lens. 

Multi-layer coating can greatly improve the transmittance of the lens. For example, the reflectivity of each surface of an uncoated lens is 5%, which is reduced to 2% after single-layer coating, and can be reduced to 0.2% with multi-layer coating. This can greatly reduce the diffuse reflection between the lenses of the lens, thereby improving the contrast and sharpness of the image.

Magnesium fluoride coating

Magnesium fluoride is a kind of coating material. Magnesium fluoride crystal (MgF ₂ ) belongs to the tetragonal system, with a melting point of 1255°C, high hardness, good mechanical properties, stable chemical properties, and not easy to deliquesce and corrode. Its main feature in optical properties is that it has a high transmittance in the vacuum ultraviolet band (the transmittance at 170nm is still above 80%). It is widely used in optical fiber communications, military fields and various optical components.

Application of magnesium fluoride coating

The main application of magnesium fluoride coating is coating on the surface of ordinary tempered glass, thereby improving the light transmittance of the tempered glass surface and achieving easy cleaning function, while also extending the life of the glass. AR coated glass can currently be mainly used in solar cell components, solar thermal, construction, automotive glass and other fields.

Preparation of magnesium fluoride coating

Magnesium fluoride coating uses evaporation method, which is called evaporation coating by heating and evaporating a certain substance to make it deposit on the solid surface. This method was first proposed by Faraday in 1857 and has become one of the commonly used coating technologies in modern times. Evaporating substances such as metals, compounds, etc. are placed in a crucible or hung on a hot wire as an evaporation source, and the substrates to be plated such as metals, ceramics, plastics, etc. are placed in front of the crucible. After the system is evacuated to a high vacuum, the crucible is heated to evaporate the substance in it, and the atoms or molecules of the evaporated substance are deposited on the surface of the substrate in a condensed manner. The film thickness can range from hundreds of angstroms to several microns. The film thickness is determined by the evaporation rate and time of the evaporation source (or by the charge amount), and is related to the distance between the source and the substrate. For large-area coating, a rotating substrate or multiple evaporation sources are often used to ensure the uniformity of the film thickness. The distance from the evaporation source to the substrate should be less than the mean free path of the vapor molecules in the residual gas to prevent chemical reactions caused by collisions between the vapor molecules and the residual gas molecules. The high-quality glass is processed on one or both sides to have a lower reflectance than ordinary glass, and the reflectivity of light is reduced to below 1%. In the visible light range, the single-sided reflectivity of ordinary glass is about 4%, and the total spectral reflectivity is about 8%.

Jiayuan has layout in both the upstream and downstream of the fluorine chemical industry chain, forming a complete fluorine chemical industry chain. At the same time, Jiayuan is also constantly conducting technological research and development and innovation, and has stronger competitiveness and market position in the production, sales and research and development of magnesium fluoride products. If you are interested in magnesium fluoride products or Jiayuan, you can visit our official website for viewing and consultation!