| 摘要 |
PROBLEM TO BE SOLVED: To obtain dielectric films which obviate the occurrence of a change with lapse of time by the lowering of a refractive index and the infiltration of water by making a film forming material incident on film forming surfaces obliquely to the normals of these surfaces to deposit the material thereon and subjecting the material to an annealing treatment. SOLUTION: The normals Va, Vb of the film forming surfaces 2a, 2b of an optical element 1 vary in the directions from each other. The material for vapor deposition contg. metallic molecules fly from a vapor deposition source in the direction of an arrow A. The incident angles to the film forming surfaces are nearly equal. The thin films formed on the film forming surfaces 2a, 2b are partly or fully formed of the metal. The metallic films grow obliquely to the film forming surfaces 2a, 2b and since nucle-growth occurs, the metallic films grow at the higher density than in the case the films grow perpendicularly. The metallic films are subjected to a post treatment, such as plasma treatment or thermal annealing treatment to oxidize the metallic molecules and to form the dielectric films. The formation of the dielectric films by one time treatment on the >=2 film forming surfaces varying in the normal directions is thus made possible. |
