Method and system for emissivity determination

Patent metadata

Field	Value
Publication number	US-9516243-B2
Application number	US-201214233672-A
Country	US
Kind code	B2
Filing date	Jul 11, 2012
Priority date	Jul 20, 2011
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A surface of an object is irradiated using an infrared light beam. The infrared light beams reflected at the object are received by an infrared camera which captures a first intensity of the reflected infrared light beams on a detector of the infrared camera. Ambient radiation reflected at the object and the characteristic radiation of the object are detected by capturing a second intensity of the reflected ambient radiation and the characteristic radiation of the object on the detector of the infrared camera. The emissivity of the object is calculated based on the first intensity and the second intensity.

First claim

The invention claimed is:

1. A method for determining emissivity of an object, comprising:
irradiating a surface of the object with an infrared light beam;
receiving reflected infrared light beams, reflected at the object, using an infrared camera having a detector with an acquisition area comprising a two-dimensional array of pixels;
acquiring a first intensity of the reflected infrared light beams at each individual pixel in the acquisition area of the detector of the infrared camera;
receiving reflected surrounding radiation reflected at the object and inherent radiation of the object using the infrared camera;
acquiring a second intensity of the reflected surrounding radiation and the inherent radiation of the object at each individual pixel in the acquisition area of the detector of the infrared camera;
for each individual pixel of the two-dimensional array of pixels in the acquisition area of the detector, adjusting the first intensity acquired at the respective pixel as a function of the second intensity acquired at the respective pixel,
calculating the emissivity of the object based on the adjusted second intensity at each pixel of the two-dimensional array of pixels.

2. The method as claimed in claim 1 , wherein said irradiating the object with the infrared light beam includes focusing infrared radiation emitted by an infrared emitter.

3. The method as claimed in claim 2 , wherein said receiving of the reflected infrared light beams and the reflected surrounding radiation as well as the inherent radiation of the object in each case comprises focusing the reflected infrared light beams on the detector with the aid of a lens device.

4. The method as claimed in claim 3 , furthermore comprising setting the focal point of the lens device on the surface of the object.

5. The method as claimed in claim 4 , wherein said acquiring the first intensity and said acquiring the second intensity each comprises integrating a received intensity over an acquisition area of the detector.

6. The method as claimed in claim 5 , further comprising:
wavelength-dependent filtering of the reflected infrared light beams with the aid of a filter device of the infrared camera; and
wavelength-dependent filtering of the reflected surrounding radiation and the inherent radiation of the object with the aid of the filter device.

7. A device for determining emissivity of an object using an infrared camera having a detector with an acquisition area comprising a two-dimensional array of pixels, comprising:
an emitter device, including:
an infrared emitter, which emits infrared light beams over a predetermined wavelength range, and
an aperture stop, which is configured to focus at least some of the infrared light beams emitted by the infrared emitter into a substantially parallel light beam and to transmit the substantially parallel light beam to a surface of the object; and

an evaluation apparatus with a control apparatus, coupled to said emitter device and the infrared camera, the control apparatus configured to:
actuate the infrared camera in acquiring an intensity of the substantially parallel light beam reflected from the surface of the object and to synchronize emission of the infrared light beams by the infrared emitter with the acquiring of the intensity by the infrared camera;
acquire a first intensity of the reflected infrared light beams at each individual pixel in the acquisition area of the detector of the infrared camera during emission of the infrared light beams by the infrared emitter;
acquire a second intensity of the reflected surrounding radiation and the inherent radiation of the object at each individual pixel in the acquisition area of the detector of the infrared camera during an absences of emission of the infrared light beams by the infrared emitter; and
for each individual pixel of the two-dimensional array of pixels in the acquisition area of the detector, adjust the first intensity acquired at the respective pixel as a function of the second intensity acquired at the respective pixel.

8. The device as claimed in claim 7 , wherein said evaluation device comprises a calculation apparatus, configured to calculate the emissivity of the object based on the intensity acquired by the infrared camera.

9. The device as claimed in claim 8 ,
wherein said calculation apparatus has a lock-in amplifier, and
wherein the control apparatus is configured to control the emission of the infrared light beams by said infrared emitter with a clock of a reference frequency.

10. A system for determining emissivity of an object, comprising:
an infrared camera, including a detector having an acquisition area comprising a two-dimensional array of pixels for acquiring intensity of infrared light beams received by said camera;
an emitter device, including:
an infrared emitter, which emits the infrared light beams over a predetermined wavelength range, and
an aperture stop, which is configured to focus at least some of the infrared light beams emitted by the infrared emitter into a substantially parallel light beam and to transmit the substantially parallel light beam to a surface of the object; and

an evaluation apparatus with a control apparatus, coupled to said emitter device and said infrared camera, the control apparatus configured to:
actuate said infrared camera in acquiring an intensity of the substantially parallel light beam reflected from the surface of the object and to synchronize emission of the infrared light beams by the infrared emitter with the acquiring of the intensity by said infrared camera;
acquire a first intensity of the reflected infrared light beams at each individual pixel in the acquisition area of the detector of the infrared camera during emission of the infrared light beams by the infrared emitter;
acquire a second intensity of the reflected surrounding radiation and the inherent radiation of the object at each individual pixel in the acquisition area of the detector of the infrared camera during an absences of emission of the infrared light beams by the infrared emitter; and
for each individual pixel of the two-dimensional array of pixels in the acquisition area of the detector, adjust the first intensity acquired at the respective pixel as a function of the second intensity acquired at the respective pixel.

11. The system as claimed in claim 10 , wherein said evaluation device comprises a calculation apparatus, configured to calculate the emissivity of the object based on the intensity acquired by the infrared camera by integrating the acquired intensity over an acquisition area of the detector.

12. The system as claimed in claim 11 , wherein said infrared camera includes a lens device which has a front focal point on the surface of the object and is configured to image the infrared light beams emitted the infrared emitter and reflected at the surface of the object, at infinity on an acquisition area of the detector.

13. The system as claimed in claim 12 , wherein the detector is arranged in a rear focal point of the lens device.

14. The system as claimed in claim 13 , wherein the infrared camera includes a filter device configured to filter reflected infrared light beams, acquired by the detector, in a wavelength-dependent manner.

Assignees

• Rothenfusser Max
• Stockmann Michael
• Siemens Ag

Inventors

• Rothenfusser Max
• Stockmann Michael

Classifications

• G01J5/0003 Primary

  for sensing the radiant heat transfer of samples, e.g. emittance meter · CPC title

• H04N23/20

  for generating image signals from infrared radiation only · CPC title

• G01J5/0896

  using a light source, e.g. for illuminating a surface · CPC title

• H04N5/33 Primary

  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) · CPC title

• G01J5/0831

  Masks; Aperture plates; Spatial light modulators · CPC title