The coating process essentially consists of seven steps. In the first step, the equipment is prepared for coating and the evaporators are filled with material. For PVD coating, these are typically oxides, fluorides, sulfides and metals such as gold, chrome, silver and aluminum. In the second step, the cleaned optics are fixed in the system. Then the vacuum chamber is closed and the vacuum pumps are started. After reaching the starting pressure, the next step is to start coating.
In the case of evaporation from a boat, this is heated by current flow until the melting point of the coating material is reached. Deposition onto the optics then occurs at a rate of a few nanometers per second. The target coating thickness of a material depends on its function. Most metals are opaque from about 100 nm after such a coating.