Method and apparatus for determining the emissivity, area and temperature of an object

• US 8,050,884 B2
• Filed: 12/06/2007
• Issued: 11/01/2011
• Est. Priority Date: 12/06/2007
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Murata, Ronald N.
• Primary Examiner(s): TEIXEIRA MOFFAT, JONATHAN CHARLES
• Application Number:
  US11/951,698
• Publication Number:
  US 20100256945A1
• Time in Patent Office: 1,426 Days
• Field of Search: 702/134, 374/9
• US Class Current: 702/134
• CPC Class Codes: G01J 2005/0074 having separate detection of emissivity
• CPC Class Codes: G01J 2005/0092 Temperature by averaging, e.g. by scan thermography G01J5/48
• CPC Class Codes: G01J 5/0003 for sensing the radiant heat transfer of samples, e.g. emittance meter
• CPC Class Codes: G01J 5/48 Thermography; Techniques using wholly visual means
• CPC Class Codes: G01J 5/602 using selective, monochromatic or bandpass filtering
• CPC Class Codes: G01J 5/80 Calibration using comparison with reference sources G01J5/52
• CPC Class Codes: G01J 5/802 by correcting for emissivity

Abstract

Methods and apparatus are provided to determine the emissivity, temperature and area of an object. The methods and apparatus are designed such that the emissivity and area of the object may be separately determined as functions dependent upon the temperature of the object derived from a three or more band infrared measurement sensor. As such, the methods and apparatus may only require a regression analysis of the temperature of the object without any regression analysis of the emissivity and area of the object.

Claims

1. A method of determining emissivity, temperature and area of an object, the method comprising:

simulating a measure of a radiant intensity of the object at each of a first wavelength, a second wavelength and a third wavelength;

forming a plurality of ratios of the measures of radiant intensity of the object, wherein each ratio is based upon a relationship of the measure of radiant intensity of the object at one wavelength to the measure of radiant intensity of the object at another wavelength;

determining the emissivity of the object as a function of the temperature of the object for each of a plurality of the ratios;

determining the area of the object as a function of the temperature of the object for each of a plurality of the ratios based upon the emissivity of the object as determined for a respective ratio and the measure of radiant intensity of the object at a wavelength other than the wavelengths associated with the respective ratio; and

determining the temperature of the object based upon the measure of radiant intensity of the object at each of the first, second and third wavelengths and the emissivity and the area of the object as determined as a function of the temperature of the object

wherein determining the emissivity, area and temperature of the object is performed by a processor.

2. A method according to claim 1 wherein each of determining the emissivity of the object and determining the area of the object comprises evaluating components of radiant intensity attributable to both emission and reflectance.

3. A method according to claim 1 wherein determining the temperature comprises determining the temperature based upon a difference between the measure of the radiant intensity of the object and a model of the radiant intensity of the object, wherein the model of the radiant intensity of the object is based upon the emissivity and the area of the object at a predefined temperature.

4. A method according to claim 3 wherein determining the temperature further comprises evaluating the difference between the measure of the radiant intensity of the object and a model of the radiant intensity of the object at each of a plurality of predefined temperatures.

5. A method according to claim 1 further comprising defining the emissivity and the area of the object for each of a plurality of the ratios based upon the determined temperature of the object.

6. A method according to claim 5 further comprising determining an average of the emissivity and the area of the object over the plurality of the ratios.

7. A method of determining emissivity, temperature and area of an object, the method comprising:

simulating a measure of a radiant intensity of the object at each of a plurality of wavelengths;

forming a plurality of ratios of the measures of radiant intensity of the object, wherein each ratio is based upon a relationship of the measure of radiant intensity of the object at one wavelength to the measure of radiant intensity of the object at another wavelength;

determining the emissivity and the area of the object as respective functions of the temperature of the object including determining the area of the object as a function of the temperature of the object for each of a plurality of the ratios based upon the emissivity of the object as determined for a respective ratio and the measure of radiant intensity of the object at a wavelength other than the wavelengths associated with the respective ratio; and

performing, with a processor, a regression analysis of the temperature of the object without separately performing a regression analysis of the emissivity and the area of the object, wherein performing the regression analysis of the temperature of the object determines the temperature of the object from which the emissivity and the area of the object are determinable.

8. A method according to claim 7 wherein determining the emissivity of the object comprises:

determining the emissivity of the object as a function of the temperature of the object for each of a plurality of the ratios.

9. A method according to claim 7 wherein determining the emissivity and the area of the object comprises evaluating components of radiant intensity attributable to both emission and reflectance.

10. A method according to claim 7 wherein performing the regression analysis of the temperature comprises determining the temperature based upon a difference between the measure of the radiant intensity of the object and a model of the radiant intensity of the object, wherein the model of the radiant intensity of the object is based upon the emissivity and the area of the object at a predefined temperature.

11. A method according to claim 10 wherein determining the temperature further comprises evaluating the difference between the measure of the radiant intensity of the object and a model of the radiant intensity of the object at each of a plurality of predefined temperatures.

12. A method according to claim 7 further comprising defining the emissivity and the area of the object based upon the determined temperature of the object.

13. An apparatus for determining emissivity, temperature and area of an object, the apparatus comprising a processor configured to simulate a measure of a radiant intensity of the object at each of a first wavelength, a second wavelength and a third wavelength, the processor also configured to determine the emissivity of the object by forming a plurality of ratios of the measures of radiant intensity of the object, wherein each ratio is based upon a relationship of the measure of radiant intensity of the object at one wavelength to the measure of radiant intensity of the object at another wavelength, the processor also configured to determine the emissivity and the area of the object as respective functions of the temperature of the object including determination of the area of the object as a function of the temperature of the object for each of a plurality of the ratios based upon the emissivity of the object as determined for a respective ratio and the measure of radiant intensity of the object at a wavelength other than the wavelengths associated with the respective ratio, and the processor further configured to perform a regression analysis of the temperature of the object without separately performing a regression analysis of the emissivity and the area of the object, wherein the processor, in the performance of the regression analysis of the temperature of the object, is configured to determine the temperature of the object from which the emissivity and the area of the object are determinable.

14. A apparatus according to claim 13 wherein the processor is further configured to determine the emissivity of the object as a function of the temperature of the object for each of a plurality of the ratios.

15. An apparatus according to claim 13 wherein the processor is configured to determine the emissivity and the area of the object by evaluating components of radiant intensity attributable to both emission and reflectance.

16. An apparatus according to claim 13 wherein the processor is configured to perform the regression analysis of the temperature by determining the temperature based upon a difference between the measure of the radiant intensity of the object and a model of the radiant intensity of the object, wherein the model of the radiant intensity of the object is based upon the emissivity and the area of the object at a predefined temperature.

17. An apparatus according to claim 16 wherein the processor is further configured to determine the temperature by evaluating the difference between the measure of the radiant intensity of the object and a model of the radiant intensity of the object at each of a plurality of predefined temperatures.

18. An apparatus according to claim 13 wherein the processor is configured to define the emissivity and the area of the object based upon the determined temperature of the object.