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Coating Service - Metals And Dielectrics

Optical coatings are suitable for filtering, reflecting or directing light rays according to intention. They are also used to improve the quality of optical components and for surface protection.

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Optical coatings increase the reflection of surfaces and are therefore used for the manufacture of high-quality optical components. In many cases, a coating of metals is sufficient to produce the desired properties of the surfaces.

These coatings are mainly used for broadband optical applications. For laser applications and special requirements, we develop optical coatings that are precisely tailored to your needs.

Convince yourself of the advantages of optical coatings:

Pleiger Overview optical coatings
Overview optical coatings

Gold-, Silver- and Aluminium layer

Very broadband optics are achieved with metallic coatings. The goal is to maximize the reflection on the surface. The specific metal is selected based on the desired properties of the coated surface. In most cases, the optical coating is applied by thermal vapor deposition in a high vacuum using PVD technology. PVD coatings are in turn divided into metallic coatings and dielectric coatings, although the range of application of metallic coatings is limited.

Metal mirrors made of

  • BK7, Fused Silica
  • Silicon
  • OFCH Copper
  • Aluminium
  • Zerodur
  • inclusive coating
overview optical coating

is the perfect choice for all applications in the IR range. However, it can only be used from a wavelength of 700 nm. Due to its low hardness, it scratches very quickly. Therefore, we recommend to provide it with an additional protective coating. Gold mirrors are often used in infrared measurement technology and in low-power laser systems.

overview optical coating

is used exclusively from VIS to IR. However, it tarnishes on contact with air. It must therefore always be given final protection with a protective coating. Of all metals, silver offers the highest reflection in the visible wavelength and infrared range. These silver mirrors are used in astronomy, laser technology (mirror telescopes) and measurement technology.

overview optical coating

is easy to evaporate (PVD) and for this reason is the prefered material for many applications from UV to NIR. It is therefore the most commonly used material for mirror fabrication. However, the reflectance of aluminum drops over time. The reason is the formation of oxide on the surface. At the same time, however, this protects surface from further oxidation.

overview optical coating

Rhodium / Platinum / Chrome
Rhodium is a high-melting precious metal that enables very hard and also chemically stable metallic coatings. Platinum is also used when a highly stable mirror surface is required. It does not tarnish and is not attacked by aggressive gases or liquids. However, the reflectivity of rhodium, platinum and chrome is lower than that achieved by metallic coatings such as gold, silver or aluminum. Due to their stability, they are nevertheless a perfect alternative for optical applications under extreme conditions.

overview optical coatings
overview optical coatings

Enhanced metal coatings

Applying dielectric layers to a metal layer increases the reflectivity of the substrates.

Designed for the UV to VIS.

Optimizable for wavelengths from 400 – 700 nm.

Coatings for CO2 lasers

Coatings for CO2 lasers are designed and manufactured for the highest demands. They are used in laser cutting, laser marking and internal optics.

R > 99,9 % @ 10,6 µm and AOI 45° (s-pole)

R > 99,7 % @ 10,6 µm and AOI 45° (p-pole)

R > 45,0 % @ 0,632 µm and AOI 45° (r-pole)

Data sheet Total Reflector

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overview optical coating

Glass coating

Coating of glass is done for the production of mirrors or lenses. Once the coating has been vapor deposited, the optics are inspected by hand. In this way, we meet the high quality demands that our customers place on us. We offer high-performance optical coating of glass, which enables extremely thin layers. We offer the right solution for the production of your optical components for almost any geometry. Applying a coating to glass is a complex process that requires modern technical equipment and innovative production processes. Important parameters are besides the refractive index, the high vacuum, the coating speed and the temperature of the substrate. The optical coating of metals improves the reflection of the surface. Our coating service coats all common optical glasses for you with the highest quality standards.

Silicon coating

Coating silicon is often used to increase reflection. Silicon is particularly lightweight and is optimized with various optical coatings for a wide range of applications. Silicon is a substrate material that is ideally suited for manufacturing lightweight, highly efficient mirrors. It is used, for example, in the manufacture of CO2 lasers. The reflection is improved by means of a dielectric coating. Thanks to their low absorption, dielectric coatings are particularly suitable for the production of laser systems which are also protected from environmental influences.

Mirror coatings: High-Power YAG and CO2 laser coatings

Antireflection coatings: AR/AR for the NIR range

Filter: Bandpass filters for gas analysis

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PVD technology

Optics are refined with a PVD coating to protect a surface against environmental influences or to improve its optical properties. The coating thicknesses applied for this purpose range from a few nanometers to a few micrometers. PVD coatings are divided into groups, which are classified as metallic and dielectric coatings. Metallic coatings have a limited range of application due to their high absorption. In contrast, dielectric coatings have low absorption and are therefore particularly suitable for laser systems.

The deposition of optical coatings is a complex process. Important parameters are the refractive index, the temperature of the substrate, the vacuum and the coating speed. The choice of materials is based on the optical, mechanical and chemical properties you need.

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The coating process essentially consists of seven steps. In the first step, the equipment is prepared for coating and the evaporators are filled with material. For PVD coating, these are typically oxides, fluorides, sulfides and metals such as gold, chrome, silver and aluminum. In the second step, the cleaned optics are fixed in the system. Then the vacuum chamber is closed and the vacuum pumps are started. After reaching the starting pressure, the next step is to start coating.

In the case of evaporation from a boat, this is heated by current flow until the melting point of the coating material is reached. Deposition onto the optics then occurs at a rate of a few nanometers per second.  The target coating thickness of a material depends on its function. Most metals are opaque from about 100 nm after such a coating. 

The thickness of transparent materials such as oxides is adapted to the application. It is thus possible to optimize the properties of a coating for a wavelength, angle of incidence or polarization.

At the end of the coating process, the optics are allowed to cool in a vacuum and the chamber is then ventilated. In the final step, we measure the reflection and transmission. In addition, tests are carried out on adhesion, abrasion resistance and stability to high humidity. Thermally applied coating systems are characterized by their low coating stresses.

Do you need optics ready for immediate use?

Here you can find our overview of optical mirrors.

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