Tuning D* with Modified Thermal Detectors

• US 20090140144A1
• Filed: 11/25/2008
• Published: 06/04/2009
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: University of South Carolina
• Inventors: Simcock, Michael N., Myrick, Michael L.
• Granted Patent: US 8,283,633 B2
• Time in Patent Office: Days
• US Class Current: 250/338.100
• CPC Class Codes: G01J 5/046 Materials; Selection of thermal materials
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G01J 5/0802 Optical filters
• CPC Class Codes: G01J 5/12 using thermoelectric elements, e.g. thermocouples

Abstract

Disclosed is apparatus and methodology for producing thermal detectors with spectral responsivities that mimic the absorptions of chemical analytes, and whose detector characteristics approach those of conventional broad-band thermal detectors. In an exemplary arrangement, the methodology provides for modification of a known Si-based thermal detector by adding a near-infrared dye absorbing film above a reflector deposited directly on the thermal detector element. The method is general to all types of thermal detectors that can be divided into separate absorber and thermal sensor components.

Claims

1. A method for adjusting the spectral detectivity of a thermal detector, comprising:

providing a thermal detector having a light sensitive portion;

coating the light sensitive portion with a first material to reduce the broadband response of the detector; and

coating the first material with a second material having spectral absorption characteristics,

whereby the spectral absorbance of the second material primarily determines the thermal conversion of the thermal detector.

2. The method of claim 1, wherein the first material is a mirror coating material.

3. The method of claim 2, wherein the mirror coating is a metal.

4. The method of claim 3, wherein the metal is silver.

5. The method of claim 1, wherein the second material is a polymer.

6. The method of claim 5, wherein the polymer comprises a near infrared dye.

7. The method of claim 6, wherein the dye absorbs light in the 860 nm spectral region.

8. The method of claim 6, wherein the dye comprises Epolight 4019.

9. The method of claim 1, wherein providing a thermal detector comprises providing a thermocouple detector.

10. The method of claim 1, wherein providing a thermal detector comprises providing a thermopile detector.

11. The method of claim 10, wherein providing a thermopile detector comprises providing a Si-based thermopile detector.

12. The method of claim 1, further comprising:

providing an electrically insulating coating on the light sensitive portion of the thermal detector prior to coating the light sensitive portion with said first material.

13. The method of claim 12, wherein the electrically insulating material is a SiO₂ film.

14. A thermal detector, comprising:

a light sensitive detector material;

a layer of light reflecting material covering at least a portion of the light sensitive material; and

a layer of spectral absorption material covering said light reflecting material.

15. A thermal detector as in claim 14, further comprising:

a layer of insulating material between said light sensitive material and said light reflecting material.

16. A thermal detector as in claim 14, wherein the light reflecting material is a metal.

17. A thermal detector as in claim 16, wherein the metal is silver.

18. A thermal detector as in claim 14, wherein the spectral absorption material is a near-infrared dye.

19. A thermal detector as in claim 18, wherein the dye is Epolight 4019.

20. A thermal detector as in claim 14, wherein the light sensitive detector is Si-based thermopile detector.