Method for producing optical element having multi-layered film

Abstract

A method for producing an optical element, in which a multi-layered film is provided on a plastic substrate, having a resistance against lights in a wavelength range of 300 nm to 450 nm, is provided. The method for producing the optical element according to the invention, is an method for producing an optical element having a multi-layered film in which a layer made of a low-refractive-index material and a layer made of a high-refractive-index material are alternately formed on a plastic substrate, the optical element being used for light in a wavelength range of 300 nm to 450 nm. The optical element producing method includes the steps of forming alternately the layer made of the low-refractive-index material and the layer made of the high-refractive-index material on the plastic substrate to produce the optical element while plasma or ionized gas is generated by a generation source in forming at least the layer made of the high-refractive-index material under a predetermined producing conditions; measuring an oxygen permeability coefficient of the produced optical element; and changing one of an output of the generation source, an ambient gas pressure in forming the layer made of the low-refractive-index material, and an ambient gas pressure in forming the layer made of the high-refractive-index material among the predetermined producing conditions when the oxygen permeability coefficient of the produced optical element is more than 30 cm·mm/(m·24 hr·atm).