Method of forming optical thin film

Abstract

A method for forming an optical thin film used for optical elements of laser systems including high-energy lasers and an optical element of optical apparatuses is provided. The optical thin film can be easily formed on a desired substrate with reproducibility by vapor-depositing a porous fluoride layer for preventing reflection in the deep ultraviolet region, and can be easily removed in a short time to reuse the substrate if the thin film damaged. A water-insoluble material (2) for preventing reflection is vapor-deposited onto an optical element substrate (1). A water-soluble material (3) having a higher particle energy is vapor-deposited onto the surface of the water-insoluble material (2). The water-soluble material (3) permeates deep into the water-insoluble material (2) to form a mixed film on the surface of the substrate (1). Then, the water-soluble material (3) is dissolved and removed to form a porous thin film (5) comprising the water-insoluble material (2).

Dependencies are inferred from the claim text.