Thermal imaging calibration systems and methods

• US 6,875,979 B2
• Filed: 10/03/2002
• Issued: 04/05/2005
• Est. Priority Date: 10/03/2002
• Status: Active Grant

• Current Assignee: Teledyne FLIR LLC (Teledyne Technologies Incorporated)
• Original Assignee: Indigo Systems Corporation (Telecom Eireann)
• Inventors: Cope, Richard D.
• Primary Examiner(s): GAGLIARDI, ALBERT J
• Application Number:
  US10/264,400
• Publication Number:
  US 20040065822A1
• Time in Patent Office: 915 Days
• Field of Search: 250/252.1, 250/330, 250/332, 250/339.03, 250/339.04, 250/339.09
• US Class Current: 250/252.1
• CPC Class Codes: H04N 17/002 for television cameras
• CPC Class Codes: H04N 25/672 between adjacent sensors or output registers for reading a single image
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

A calibration assembly employs a thermoelectric cooler to provide a calibration temperature for one calibration flag and a different calibration temperature for a second calibration flag. Either calibration flag is immediately available for insertion into the optical path when calibration of the thermal imaging device is required. Consequently, the time required to calibrate a thermal imaging device within a thermal imaging system is greatly reduced.

Claims

1. A calibration flag assembly comprising:

a main body;

a first calibration flag coupled to the main body;

a first thermoelectric cooler coupled to the main body; and

a second calibration flag coupled to the first thermoelectric cooler.

2. The calibration flag assembly of claim 1, wherein the first calibration flag reaches a first calibration temperature and the second calibration flag reaches a second calibration temperature at approximately the same time upon operation of the first thermoelectric cooler.

3. The calibration flag assembly of claim 1, further comprising at least one temperature-sensing device coupled to the main body, the first calibration flag, or the second calibration flag.

4. The calibration flag assembly of claim 3, wherein the temperature sensing device comprises a thermistor.

5. The calibration flag assembly of claim 1, wherein the first thermoelectric cooler is coupled to the main body using an adhesive bond.

6. The calibration flag assembly of claim 1, wherein the main body, the first calibration flag, and the second calibration flag are made of a thermally conductive material.

7. The calibration flag assembly of claim 6, wherein the thermally conductive material comprises a metal, a metal alloy, or a ceramic material.

8. The calibration flag assembly of claim 1, further comprising a second thermoelectric cooler coupled to the main body, wherein the second thermoelectric cooler assists the first thermoelectric cooler to bring the first calibration flag to a desired calibration temperature.

9. The calibration flag assembly of claim 1, wherein the calibration flag assembly is incorporated into a thermal imaging system to assist in calibrating a sensor of the thermal imaging system.

10. The calibration flag assembly of claim 9, wherein the calibration flag assembly forms part of a filter wheel assembly that includes an optical filter, with the optical filter, the first calibration flag, or the second calibration flag being selectively insertable into an optical path of the thermal imaging system.

11. A method of calibrating a thermal imaging device with a calibration flag assembly having a main body, method comprising:

operating a first thermoelectric cooler to adjust a temperature of a first calibration flag and a second calibration flag to a first calibration temperature and a second calibration temperature, respectively, wherein the first thermoelectric cooler and the first calibration flag are coupled to the main body and the second calibration flag is coupled to the first thermoelectric cooler;

inserting into an optical path of the thermal imaging device the first calibration flag; and

inserting into the optical path the second calibration flag.

12. The method of claim 11, further comprising:

acquiring a first set of data from the thermal imaging device when the first calibration flag is inserted into the optical path; and

acquiring a second set of data from the thermal imaging device when the second calibration flag is inserted into the optical path.

13. The method of claim 12, further comprising performing an offset adjustment or a gain adjustment using the first and second set of data acquired.

14. The method of claim 12, further comprising operating a second thermoelectric cooler to assist the first thermoelectric cooler in adjusting a temperature of the first calibration flag to the first calibration temperature.

15. A thermal imaging system comprising:

a thermal imaging sensor adapted to receive thermal radiation through an optical path; and

a calibration flag assembly that provides thermal calibration images, when inserted into the optical path, to assist in performing non-uniformity calibration, wherein the calibration flag assembly comprises;

a main body;

a first calibration flag coupled to the main body;

a first thermoelectric cooler coupled to the main body; and

a second calibration flag coupled to the first thermoelectric cooler.

16. The thermal imaging system of claim 15, wherein the first thermoelectric cooler is operable to adjust a temperature of the first calibration flag to a first calibration temperature and to adjust a temperature of the second calibration flag to a second calibration temperature.

17. The thermal imaging system of claim 16, further comprising at least one temperature-sensing device coupled to the calibration flag assembly.

18. The thermal imaging system of claim 17, further comprising a second thermoelectric cooler coupled to the calibration flag assembly, wherein the second thermoelectric cooler is operable to assist the first thermoelectric cooler in adjusting a temperature of the first calibration flag to the first calibration temperature.

19. The thermal imaging system of claim 15, further comprising means for inserting the calibration flag assembly into the optical path.

20. The thermal imaging system of claim 19, wherein the insertion means comprises:

a prime mover; and

an assembly coupled to the prime mover and to the calibration flag assembly, wherein the prime mover is operable to move the assembly, which results in the insertion of the first calibration flag or the second calibration flag into the optical path.

21. The thermal imaging system of claim 20, further comprising an optical filter coupled to the assembly, wherein the prime mover is operable to rotate the assembly, which results in the insertion of the optical filter, the first calibration flag, or the second calibration flag.