The eta plus coating is a ceramic metal compound.

This so-called CERMET (ceramic metal compound) is comprised of several single layers in which metal particles are embedded in a ceramic matrix. Due to scattering effects, they absorb radiation within a certain wavelength range.

The metal content of the eta plus coating system gradually decreases towards the surface.


The coating applied to the surface of the substrate is a passivating metal coating. It serves as a diffusion barrier as well as a means of corrosion protection for the metal substrate.
The inner layers are the functional layers, in which most of the light is absorbed.
The top layer is a pure ceramic and also serves as an anti-reflection coating and as an extremely durable protection for the entire system.