Astrooptics
Application
The G4000MR vacuum coating system is a production-scale coater designed for producing uniform reflective and protective coatings on large-size optical articles including astronomical primary mirrors.
Engineering and Technology
Configuration of the coater and features of the deposition process are developed specifically to process articles of up to 4 meters in diameter with small software-controlled magnetrons moving along a calculated path at adjustable speed. Magnetrons movement speed and mirror rotation speed is matched to achieve exceptionally uniform coating thickness. The mirror is positioned face down and is rotated several times during the cycle.
The G4000MR is intended for depositing reflection coatings of aluminum, silver and other metals. Silicon oxide layer on top of the reflection coating ensures wear resistant protective features of the coating stack. Before coating deposition, the mirror face is plasma-treated with a movable ion source to ensure good adhesion. Coating is deposited with metal and reactive magnetron sputtering processes. The circular magnetrons are powered with pulsed-DC power supplies. Devices on the basis of comprising quartz-crystal resonators are used for controlling the deposition rate of the growing thin film.
The vacuum required for coating is ensured by refrigerator cryo-pumps and a turbo pump connected to Roots blower and dry compressing pumps.
The control system ensures fully automated process.
The coater and coating process can be customized to the requirements of the respective customer.
Data Sheet
Substrate: large-size astronomical glassceramic mirrors
Substrate diameter: up to 4 m
Number of substrates: 1 pc.
Coating: Al, Ag, SiO2, SiNx, NiCr etc.
Pretreatment: DC Gridded Ion Source
Deposition sources: 3 circular planar magnetrons
Floor space requirement (L x W x H): 23 x 14 x 5.15 m