Optical filter screening out infrared and ultraviolet light

• US 7,212,336 B2
• Filed: 05/03/2006
• Issued: 05/01/2007
• Est. Priority Date: 07/01/2005
• Status: Expired due to Fees

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Chen, Ga-Lane, Chang, Ching-Chou
• Primary Examiner(s): Nguyen; Thong Q.
• Application Number:
  US11/416,725
• Publication Number:
  US 20070002432A1
• Time in Patent Office: 363 Days
• Field of Search: 359350-361, 359/557, 359/590
• US Class Current: 359/359
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361

Abstract

An optical filter includes a transparent substrate, a first film stack and a second film stack. The first and second film stacks each includes a number of high refractive index layers and a number of low refractive index layers alternately stacked one on another. The first film stack is defined as (HL)⁷(0.76H0.76L)⁶, and the second film stack is defined as 0.5(HL)(1.3H1.3L)⁹(HL)⁸, wherein, H represents a high refractive index layer having a base optical thickness equal to one fourth of a first reference wavelength associated with the optical filter, L represents a low refractive index layer having a base optical thickness equal to one fourth of a first 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.

Claims

1. An optical filter for screening out infrared and ultraviolet light, comprising:

a transparent substrate having a first surface and an opposite second surface;

a first film stack formed on the first surface of the substrate; and

a second film stack formed on the second surface of the substrate, the first and second film stacks each comprising a plurality of high refractive index layers and a plurality of low refractive index layers alternately stacked one on another, wherein the first film stack is defined as follows;

(HL)⁷(0.76H0.76L)⁶

wherein H represents a high refractive index layer having a base optical thickness equal to one fourth of a first 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 first reference wavelength associated with the optical filter, the expression enclosed in each parenthesis represents a filter cavity, and superscripts represent the number of repetitions of the expression enclosed in the parenthesis;

the second film stack is defined as follows;

0.5(HL)(1.3H1.3L)⁹(HL)⁸

wherein, H represents a high refractive index layer having a base optical thickness equal to one fourth of a second 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 second reference wavelength associated with the optical filter, the expression enclosed in each parenthesis represents a filter cavity, and the superscript represents the number of repetitions of the expression enclosed in the parenthesis.

2. The optical filter as claimed in claim 1, wherein the high refractive index layer is made of a material selected from the group consisting of titanium dioxide (TiO₂), titanium pentoxide (TiO₅) and tantalum pentoxide (Ta₂O₅), the low refractive index layer is made of a material selected from the group consisting of silicon dioxide (SiO₂) and aluminum oxide (Al₂O₃).

3. The optical filter as claimed in claim 1, further comprising an anti-reflective film configured between the first film stack and the first surface of transparent substrate.

4. The optical filter as claimed in claim 3, further comprising an anti-reflective film configured between the second film stack and the second surface of transparent substrate.

5. The optical filter as claimed in claim 3, wherein the anti-reflective film is comprised of a plurality of high refractive index layers and a plurality of low refractive layers alternately stacked one on another.

6. The optical filter as claimed in claim 5, wherein the anti-reflective film is composed of two Ti₃O₅ layers and two SiO₂ layers.

7. The optical filter as claimed in claim 6, wherein respective thickness coefficients of the two Ti₃O₅ layers are 0.301, 2.546, and the respective thickness coefficients of the two SiO² layers are 0.421, 1.137.

8. An optical filter for screening out infrared and ultraviolet light, comprising:

a transparent substrate having a first surface and an opposite second surface;

a first film stack formed on the first surface of the substrate; and

a second film stack formed on the second surface of the substrate, the first and second film stacks each comprising a plurality of high refractive index layers and a plurality of low refractive index layers alternately stacked one on another, each high refractive index layer is made of TiO₂, each low refractive index layer is made of SiO₂, wherein the first film stack is defined as follows;

(a₁Ha₂L)⁷(b₁Hb₂L)⁶

wherein, H represents a high refractive index layer having a base optical thickness equal to one fourth of a first reference wavelength associated with the optical filter, L represents a low reference index layer having a base optical thickness equal to one fourth of the first reference wavelength associated with the optical filter, the expression enclosed in each parenthesis represents a filter cavity, and the superscript represents the number of repetitions of the expression enclosed in the parenthesis;

the second film stack is defined as follows;

0.5(c₁Hc₂L)(d₁Hd₂L)⁹(e₁He₂L)⁸

wherein, H represents a high refractive index layer having a base optical thickness equal to one fourth of a second reference wavelength associated with the optical filter, L represents a low reference index layer having a base optical thickness equal to one fourth of the second reference wavelength associated with the optical filter, a₁ is in the range from 0.372 to 1.064, a₂ is in the range from 0.962 to 1.203, b₁ is in the range from 0.477 to 0.946, b₂ is in the range from 0.389 to 2.183, c₁ is 0.130, c₂ is 0.274, d₁ is in the range from 1.217 to 1.312, d₂ is in the range from 1.231 to 1.372, e₁ is in the range from 0.940 to 1.069, e₂ is in the range from 0.544 to 1.105, the expression enclosed in each parenthesis represents a filter cavity, and the superscript represents the number of repetitions of the expression enclosed in the parenthesis.