Wavelength specific coating for mirrored optics and method for reducing reflection of white light

• US 6,822,788 B2
• Filed: 06/02/2003
• Issued: 11/23/2004
• Est. Priority Date: 10/27/2000
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Blitstein, Jeffrey L.
• Primary Examiner(s): ASSAF, FAYEZ G
• Application Number:
  US10/453,446
• Publication Number:
  US 20040008406A1
• Time in Patent Office: 540 Days
• Field of Search: 359/356, 359/350, 359/885, 359/361, 359/351, 252/587, 250/338.1, 250/330, 250/332, 250/353, 428/334, 427/577
• US Class Current: 359/350
• CPC Class Codes: G02B 5/0808 having a single reflecting layer G02B5/0883, G02B5/0891 take precedence
• CPC Class Codes: G02B 5/0866 incorporating one or more organic, e.g. polymeric layers
• 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

Abstract

An amorphous diamond coating applied onto mirrored optics in an infrared motion sensor to block specific wavelengths of energy from a “white light” source like a halogen lamp, without reducing the reflectivity of the mirror surface in the Mid-Infrared wavelengths. A specific thickness of diamond-like-coating is applied on top of the reflective metal surface of a mirrored part, thereby reducing the mirror'"'"'s reflectivity at visible and near-Infrared wavelengths known to be problematic for IR motion sensors, such as those emitted from halogen lamps. The coating has no significant detrimental effect on mid-Infrared reflectivity, so the IR motion sensor'"'"'s performance is otherwise unaffected.

Claims

1. A method of reducing the incidence of visible and near-infrared light impinging on a reflective surface of an optical reflector in a motion sensor, comprising:

overlaying said reflective surface with a layer of non-crystalline carbon material;

said layer of non-crystalline carbon material having a thickness ranging from approximately 600 angstroms to approximately 1000 angstroms;

wherein said layer of non-crystalline carbon material absorbs visible and near-infrared light;

wherein said reflective surface reflects mid-infrared light passing through said layer of non-crystalline carbon material for detection by an infrared detector; and

wherein said layer of non-crystalline carbon material has an absorption spectra which is adjustable by adjusting said thickness.

2. A method as recited in claim 1, wherein said non-crystalline carbon material comprises amorphous diamond.

3. A method as recited in claim 1, wherein said non-crystalline carbon material comprises a diamond-like coating.

4. A method of reducing the incidence of visible and near-infrared light impinging on a reflective surface of an optical reflector, comprising:

coating said reflective surface with a diamond-like coating having a thickness ranging from approximately 600 angstroms to approximately 1000 angstroms;

wherein said diamond-like coating absorbs visible and near-infrared light;

wherein said reflective surface reflects mid-infrared light passing through said diamond-like coating for detection by an infrared detector;

and wherein said diamond-like coating has an absorption spectra which is adjustable by adjusting said thickness.

5. A method as recited in claim 4, wherein said diamond-like coating comprises a non-crystalline carbon material.

6. A method as recited in claim 4, wherein said diamond-like coating comprises an amorphous diamond material.

7. A mirror for a motion sensor having an infrared detector, comprising:

(a) a substrate base;

(b) a layer of reflective material adjacent to said substrate base; and

(c) a light absorbing layer adjacent to said layer of reflective material;

(d) said light absorbing layer having a thickness ranging from approximately 600 angstroms to approximately 1000 angstroms;

(e) wherein said light absorbing layer absorbs visible and near-infrared light;

(f) wherein said layer of reflective material reflects mid-infrared light passing through said light absorbing layer for detection by said infrared detector; and

(g) wherein said light absorbing layer has an absorption spectra which is adjustable by adjusting said thickness.

8. A mirror as recited in claim 7, wherein said light absorbing layer comprises a non-crystalline carbon material.

9. A mirror as recited in claim 7, wherein said light absorbing layer comprises an amorphous diamond material.

10. A mirror as recited in claim 7, wherein said light absorbing layer comprises a diamond like coating.

11. A mirror for a motion sensor having an infrared detector, comprising:

(a) a substrate base;

(b) a layer of reflective material adjacent to said substrate base; and

(c) a diamond-like coating over said layer of reflective material;

(d) said layer of reflective material comprising chrome;

(e) said diamond-like coating having a thickness ranging from approximately 600 angstroms to approximately 1000 angstroms;

(f) wherein said layer of reflective material mid-infrared light passing through said diamond-like coating for detection by said infrared detector; and

(g) wherein said diamond-like coating has an absorption spectra which is adjustable by adjusting said thickness.

12. A mirror as recited in claim 11, wherein said diamond-like coating comprises a non-crystalline carbon material.

13. A mirror as recited in claim 11, wherein said diamond-like coating comprises an amorphous diamond material.

14. A mirror for a motion sensor having an infrared detector, comprising:

(a) a substrate base;

(b) a layer of reflective material adjacent to said substrate base; and

(c) a layer of non-crystalline carbon material adjacent to said layer of reflective material, wherein said layer of reflective material is between said substrate base and said layer of non-crystalline carbon material;

(d) said layer of reflective material comprising chrome having a thickness of approximately 1700 angstroms;

(e) said layer of non-crystalline carbon material having a thickness ranging from approximately 500 angstroms to approximately 1000 angstroms;

(e) wherein said layer of non-crystalline carbon material absorbs visible and near-infrared light;

(f) wherein said layer of reflective material reflects mid-infrared light passing through said layer of non-crystalline carbon material for detection by said infrared detector; and

(g) wherein said layer of non-crystalline carbon material has an absorption spectra which is adjustable by adjusting said thickness.

15. A mirror as recited in claim 14, wherein said non-crystalline carbon material comprises a diamond-like coating.

16. A mirror as recited in claim 15, wherein said non-crystalline carbon material comprises an amorphous diamond material.