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Optical coating materials

An optical coating involves the plating of one or more dielectric (or metal) films on the surface to an optical component. It is intended to increase or reduce the reflectivity, beam separations, color separations, filtering, and polarizations of light.
The two most commonly used methods for coating are vacuum-coatingand electroless coat.
Principle of optocoating:
Vacuum coating:
Vacuum coating mostly refers the coatings which need to take place in a higher vacuum. This includes vacuum ion and magnetron evaporate, vacuum sputtering and molecular beam epitaxy. It is used for a target or as medicine material. You can place the substrate in the same space as your target.
The evaporation coating is usually the target of heating so that the surface components evaporate in the form of free radicals or ions and are deposited on the surface of the substrate by film-forming method (scattering island structure-trapezoidal structure-layered growth).
Derelict coating
It’s easy to see how the sputtered layer is formed.
A characteristic of an optical film is its smooth surface. An interface between the layers has been segmented in a geometrical manner. While the refractiveindex of the film can jump at that interface, it is constant within the film.
Medium for absorption: It may be uniform or normal. The actual application of the film will be much more complicated than for ideal films. A diffusion interface is created by mutual penetration between films. It forms anisotropy due to film structure, growth and stress.
The most popular optical coating materials for the eye are:
1. Metal (alloy): germanium, chromium, aluminum, silver, gold, etc.
A rare metal which is not toxic and nonradioactive. It is used mostly in semiconductor industry and infrared optic devices. Its light transmission range includes 2000NM muri-14000NM of judicial nasty 4, or more.
Sometimes used in scopes as a “colloid coating” to increase adhesion. While the limit of the colloid layer is usually 550NM. With the aid of an aluminum mirror layer, 30NM is the most effective value to maximize adhesion.
It offers the brightest reflections among the common metals in the ultraviolet, with a thickness greater than 50NM.
If the evaporation is rapid enough and the substrate temperatures are not too high, then silver can reflect as well as aluminum. This happens because of the large accumulations at low speed, which lead to higher absorption.
This material has the highest reflection among all materials.
2. Oxides.
Yttrium trioxide.
With electron gun Evaporation, properties vary according to the thickness of the films. It is 8% at 500nm. This aluminum protective film has been very popular, due to the fact that it’s extremely reflective in the 800–12000nm zone.
Cerium dioxide.
Cerium dioxide is evaporated at high density using tungsten boat heating. You can obtain low absorption thin nylon films in the range of 0.35 nm by using oxygen ion plating.
The refractive indice is the wavelength of light transmitted at 2.21500nm. High refractive Index and relative firmness make this material popular among people for their anti-reflection and splitter film applications.
Silicon dioxide.
The crystal is transparent and colorless, has high melting points, hardness, chemical stability and low melting temperatures. The crystal’s purity is excellent, and it can be used for Si02 coatings. It can also be broken down into visible, infrared or ultraviolet light, depending on its intended use. You will see pores in the film, and it will become fragile. On the other hand, films with high pressure will absorb the water, and will cause the refractive to index to increase.
Zirconium dioxide.
White heavy crystals have high levels of refractive indices and resistance to heat, chemical properties that are stable and very pure. This crystal can be used for many purposes, including to produce high quality zirconia coated without breaking point. It will diffuse the incident sunlight and decrease the lens’ light transmittance. Some incident light sources, such as those that emit high frequencies of radiation from the sun, will be affected by the optical rotation. The material that absorbs the red light is green. However, you can remove these elements of poor processing as much as is possible.
Hafnium oxide.
After it has evaporated at 150C with an electron gun, the refractiveindex will be approximately 2.0C. An oxygen-ion assisted plating technique can give stable refractive values of 2.5-2.1. For the protection of the aluminum outer layer in the range of 8000-12000NM, HFO2 is superior to SiO2.
3. Fluoride.
Magnesium fluoride.
An antireflective material with a thickness of 4 waves, it’s widely used in glass optical films.
Calcium fluoride & bariumfluoride.
Their weakness is the inability to compact completely. They have a limited use in the infrared, as they are sensitive to transmittance shifts and can be seen at longer wavelengths at higher temperatures.
It’s a UV-resistant material with high refractive index. When used in 300nm the refractive factor decreases when it contacts molybdenum/tantalum and tungsten vessels. This is why platinum or ceramic dishes should be used.
4. You may also be interested in other compounds.
Zinc sulfide.
With a refractive index from 2.35400-13000m, the light transmission range is good for environmental durability and has high stress. Mainly used to make spectroscopic film.
Lead soap.
It is an IR materials with high refractive. This thin film material can be transparent for 300 to 4000NM. The sublimation of the material occurs in the far-infrared. A substrate temperature of 250C can be beneficial. This is a good way to protect your health. It is effective when 40000NM of it is present. There are many other materials that can be used with the infrared edge of 14000NM.
Silicon dioxide Price
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