OPTICAL FILTER

• US 20060198025A1
• Filed: 02/14/2006
• Published: 09/07/2006
• Est. Priority Date: 03/04/2005
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Chen, Ga-Lane
• Granted Patent: US 7,450,306 B2
• Time in Patent Office: Days
• US Class Current: 359/588
• CPC Class Codes: G02B 5/288 comprising at least one thin film resonant cavity, e.g. in bandpass filters

Abstract

An optical filter (100) includes a substrate (110), a number of contiguous identical lower filter cavities (120) formed on the substrate and a number of contiguous upper filter cavities (130) formed on the lower filter cavities. Each of the lower filter cavities consists of two high refractive index layers (121) and one low refractive index layer (122) sandwiched between the high refractive index layers. Each of the upper filter cavities consists of two low refractive index layers (132) and one high refractive index layer (131) sandwiched between the low refractive index layers. The present invention calculates optimal thicknesses for each layer, so that can shield infrared and ultra violet radiation precisely.

Claims

1. An optical filter comprising:

a substrate;

a plurality of contiguous identical lower filter cavities formed on the substrate;

each of the lower filter cavities consisting of two high refractive index layers and one low refractive index layer sandwiched between the high refractive index layers and

a plurality of contiguous upper filter cavities formed on the lower filter cavities;

each of the upper filter cavities consisting of two low refractive index layers and one high refractive index layer sandwiched between the low refractive index layers.

2. The optical filter as claimed in claim 1, wherein each high refractive index layer of the lower filter cavities has a thickness equal to 0.5 times one eighth of a central wavelength associated therewith.

3. The optical filter as claimed in claim 1, wherein each low refractive index layer of the lower filter cavities has a thickness equal to 0.5 times one fourth of a central wavelength associated therewith.

4. The optical filter as claimed in claim 1, wherein the plurality of upper filter cavities comprises a first filter cavity having a high refractive index layer thereof having a thickness equal to 1.666 times one fourth of a central wavelength associated therewith, and low refractive index layers thereof each having a thickness equal to 1.666 times one eighth of a central wavelength associated therewith, second filter cavities each having a high refractive index layer thereof having a thickness equal to 1.4 times one fourth of a central wavelength associated therewith, and low refractive index layers thereof each having a thickness equal to 1.4 times one eighth of a central wavelength associated therewith, a third filter cavity having a high refractive index layer thereof having a thickness equal to 1.6 times one fourth of a central wavelength associated therewith, and low refractive index layers thereof each having a thickness equal to 1.6 times one eighth of a central wavelength associated therewith, and fourth filter cavities each having a high refractive index layer thereof having a thickness equal to 1.8 times one fourth of a central wavelength associated therewith, and low refractive index layers thereof each having a thickness equal to 1.8 times one eighth of a central wavelength associated therewith.

5. The optical filter as claimed in claim 1, wherein the material of the high refractive index layer is selected from one of tantalum pentoxide (Ta.sub.20.sub.5) and titanium dioxide TiO.sub.2).

6. The optical filter as claimed in claim 1, wherein the material of the low refractive index layer is selected from one of silicon dioxide (SiO.sub.2) and alumina (Al.sub.20.sub.3).

7. The optical filter as claimed in claim 1, wherein the material of the high refractive index layer is selected from one of nano tantalum pentoxide (Ta.sub.20.sub.5) and nano titanium dioxide (TiO.sub.2).

8. The optical filter as claimed in claim 1, wherein the material of the low refractive index layer is selected from one of nano silicon dioxide (SiO.sub.2) and nano alumina (Al.sub.20.sub.3).

9. The optical filter as claimed in claim 1, wherein the number of total layers thereof is in the range from 30 to 60.

10. The optical filter as claimed in claim 1, wherein the central wavelength associated with the optical filter is configured in the range from 400 nm to 700 nm.