VTD Vakuumtechnik Dresden GmbH
Niedersedlitzer Straße 75
01257 Dresden

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


Reflecting telescopes are mainly operated in the visible spectral range and near infrared spectrum. The mirrors, in particular the main mirror, are the key components of a telescope.

The main mirror's design, size, weight, material and handling possibilities on the one hand and the desired optical characteristics on the other call for tailor-made deposition systems.

Aluminium with or without a protective coating and silver with a protective coating are often used as a reflection coating, though other metals are also available.

The coating process is selected on the basis of physical and mechanical considerations. Magnetron sputtering or resistive evaporation are the most common processes in this field. Electron beam evaporation is rarely used.

The vacuum required for coating is mostly generated by refrigerator cryo-pumps or oil diffusion pumps in connection with mechanically or nitrogen-cooled Meissner-type cold traps.

The mirrors are positioned face up or face down. They rotate several times or just once to achieve a highly uniform film thickness. Another configuration is characterised by a coating source arrangement which ensures that the mirror coating can also be successfully applied without rotating the mirror.

ASTA 2400

ASTA 2400 ASTA 2400 open

ASTA 2800

ASTA 2800