The coating is carried out in a large vacuum device called an autoclave. An electron gun is heated from below to vaporize the coating material (about 300℃) so that the film is evenly attached to the lens.The excess reflection of the lens is about 10% before coating, but less than 1% after coating

The coating material is heated in a vacuum inside the device so that it evaporates and dissolves and adheres to the surface of the lens.