Patent ID: 6671109
Filing Date: 2003-12-30
Classification: C23C,G02B

Abstract:
A neutral density filter for absorbing an incident light, comprising:a substrate made of a transparent material; and a multi-layer structure of thin films laminated on the substrate, the multi-layer structure containing a transparent thin film composed of a dielectric material effective to transmit the incident light and a non-transparent thin film effective to absorb a part of the incident light, wherein the non-transparent thin film is composed of a metal material which is deposited by vacuum evaporation, the non-transparent thin film containing an oxide of the metal material, which is generated during the vacuum evaporation by introducing a gas containing an oxygen while maintaining a vacuum degree in a range of 1Ã—10âˆ’3Pa to 1Ã—10âˆ’2Pa, and which is deposited concurrently with the metal materials.