Introduction to design thought of a large vacuum sputtering coating plant for astronomical telescope .The coating plant is square and all working cells are installed on a holder inside the chamber. When the plant door open, the holder with working cells is hauled out of chamber, then maintaining, repair and installing mirrors are very easy. Metal film and dielectric film are made with DC and RF magnetron sputtering respectively. The largest diameter of mirror is 1600 mm and the diameter of sputtering target is 160 mm.

The whole mirror is coated by the polar coordinate scanning through computer control. There are three advantage: large mirror is sputtered with small power supply, so the cost is saved; By computer controlling working parameter of scanning, better uniformity can achieve; scanning sputtering can correct the mirror surface.