Optical filter for screening out infrared and ultraviolet light

• US 7,215,466 B2
• Filed: 05/12/2006
• Issued: 05/08/2007
• 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:
  US11/433,137
• Publication Number:
  US 20070002433A1
• Time in Patent Office: 361 Days
• Field of Search: 359350-361, 359557-590
• US Class Current: 359/359
• CPC Class Codes: F21V 9/04 for filtering out infrared radiation dichroic reflectors F21V7/22; using liquid-filled chambers F21V9/12
• CPC Class Codes: F21V 9/06 for filtering out ultraviolet radiation
• 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 5/282 reflecting for infrared and transparent for visible light, e.g. heat reflectors, laser protection
• CPC Class Codes: G02B 5/283 designed for the ultraviolet

Abstract

An optical filter for screening out infrared and ultraviolet light includes a transparent substrate and a film stack formed on the substrate. The film stack includes a number of high refractive index layers and a number of low refractive index layers alternately stacked one on another. 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 a reference wavelength associated with the optical filter, expressions enclosed in each parenthesis represent filter cavities, and superscripts represents the number of repetitions of the expression enclosed in that parenthesis.

Claims

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)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.

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 and-reflective film disposed on the substrate opposite to the film stack.

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

5. The optical filter as claimed in claim 4, wherein the anti-reflective film is composed of two Ti₃O₅layers and two SiO₂layers.

6. The optical filter as claimed in claim 5, wherein respective thickness coefficients of the two Ti₃O₅layers are 0.301 and 2.546, and the respective thickness coefficients of the two SiO₂ layers are 0.421 and 1.137.

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

a transparent substrate, and 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, the high refractive index layer is made of TiO₂, the low refractive index layer is made of SiO₂, the film stack being represented as follows;

(a₁Ha₂L)⁷(b₁Hb₂L)⁷(c₁Hc₂L)⁶(d₁Hd₂L)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, a₁ is in the range from 3.169 to 3.721, a₂ is in the range from 2.904 to 3342, b₁ is in the range from 2.519 to 2.804, b₂ is in the range from 2.472 to 2.982, c₁ is in the range from 0.799 to 0.998, c₂ is in the range from 0.665 to 1.185, d₁ is in the range from 0.246 to 1.004, d₂ is in the range from 0.594 to 1.221, 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.

8. The optical filter as claimed in claim 7, further comprising an anti-reflective film disposed on the substrate opposite to the film stack.

9. The optical filter as claimed in claim 8, 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.

10. The optical filter as claimed in claim 9, wherein the anti-reflective film is composed of two Ti₃O₅ layers and two SiO₂ layers.

11. The optical filter as claimed in claim 10, wherein respective thickness coefficients of the two Ti₃O₅ layers are 0.301 and 2.546, and the respective thickness coefficients of the two SiO₂ layers are 0.421 and 1.137.