METHOD FOR PRODUCING OPTICAL THIN FILM, AND ABSORPTIVE MULTILAYERED FILM ND FILTER

摘要

PROBLEM TO BE SOLVED: To provide a method for forming a film, by which an optical thin film such as an absorptive multilayer film ND filter suitable for a camera module that is required to be thinner can be formed without causing thermal creasing even when the optical thin film is formed on a thin transparent resin film substrate.SOLUTION: A protective tape 20a having a pressure-sensitive adhesive layer with an adhesive force of 0.03 to 1.20 N/cm is stuck to a first surface of a transparent resin film substrate 1; and an optical thin film is formed on a second surface of the substrate, the second surface having no protective tape 20 stuck thereto by a vacuum film forming method. Then a protective tape having a pressure-sensitive adhesive layer is stuck to the second surface where the optical thin film has been formed; and the protective tape stuck to the first surface is peeled off. Then an optical thin film is formed by a vacuum film forming method on the first surface of the transparent resin film substrate where the protective tape has been peeled.