Patent ID: 7215466

Claim:
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) 7 (2.5H2.5L) 7 (HL) 6 (0.76H0.76L) 6 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.