VTD Vakuumtechnik Dresden GmbH
Niedersedlitzer Straße 75
01257 Dresden

Phone:+49 351 - 2805-0
Fax:+49 351 - 2805-240

Optical coating - principles

The parts to be coated are carried into the vacuum chamber of the deposition plant by a customised carrier system and rotate once or several times on planetary wheels above the technical units.

A pump system consisting of combined mechanical pumps and a high-vacuum pump is responsible for generating the required working vacuum of < 5 x 10-6 mbar. Oil diffusion pumps, cryo-pumps or even turbo-molecular pumps are preferably installed depending on the technology.

A position-variable radiation heater for heating up the parts and a topographically adjusted glow discharge device for cleaning and activating the substrate surfaces are provided depending on the requirements of the respective substrate material. Standard coating is performed by an electron beam evaporator with a power spectrum of 6 to 15 kW or resistance-heated evaporator sources (helical filament or boat). An ion-assisted evaporation process has proven suitable for some applications and particularly for the coating of plastic elements (Components). Sputter sources can be used as an alternative.

Quartz crystal or optical film thickness monitors are provided for measuring and limiting the film thickness and controlling the deposition rate according to the respective technology.

Various metals and dielectrics can be employed as a coating material depending on the component's desired functionality.