The coating plant for the VLT

View of the lower part of the VLT coating plant. The coating unit is a large vacuum chamber with a diameter of 9.4 meters and a volume of about 122,000 liters. The required ultra-high vacuum is generated by 8 cryo-pumps which are located on top of the vacuum chamber. The chamber is divided into two halves by a horizontal flange sealed by two large O-rings. The mirror is loaded into the lower half of the chamber onto a whiffle-tree support system with 27 axial pads and laterally secured inside the central hole by 6 pads.