Patent ID: 7215466
Filing Date: 2007-05-08
Classification: F21V,G02B

Abstract:
1. An optical filter for screening out infrared and ultraviolet light, comprising: a transparent substrate, a film stack formed on the substrate, the film stack comprising a plurality of high refractive index layers and a plurality of low refractive index layers alternately stacked one on another, wherein the film stack is represented as follows: (3.5H3.5L) wherein H represents a high refractive index layer having a base optical thickness equal to one fourth of a reference wavelength associated with the optical filter, L represents a low refractive index layer having a base optical thickness equal to one fourth of said reference wavelength associated with the optical filter, the expression enclosed in each parenthesis represents a filter cavity, and the superscript represents the number of repetition of the expression enclosed in that parenthesis.