Patent ID: 7894148
Filing Date: 2011-02-22
Classification: C23C,G02B

Abstract:
1. An absorption type multi-layer film neutral density (ND) filter comprising a substrate formed of a resin film and provided on at least one side thereof an absorption type multi-layer film formed of oxide dielectric film layers and absorption film layers which are alternately formed in layers, wherein; the oxide dielectric film layers are each constituted of an SiCyOx (0<y≦0.1, 1.5<x<2) film having an extinction coefficient at a wavelength of 550 nm of 0.005 to 0.05, formed by a physical vapor deposition process making use of a film-forming material composed chiefly of SiC and Si, and the absorption film layers are each constituted of a metal film having a refractive index at a wavelength of 550 nm of 1.5 to 3.0 and an extinction coefficient at that wavelength of 1.5 to 4.0, formed by a physical vapor deposition process; an outermost layer of the absorption type multi-layer film being constituted of one oxide dielectric film layer formed of the SiCyOx film.