Infrared sensor array with alternating filters

Patent metadata

Field	Value
Publication number	US-11415465-B2
Application number	US-201916428898-A
Country	US
Kind code	B2
Filing date	May 31, 2019
Priority date	Dec 5, 2016
Publication date	Aug 16, 2022
Grant date	Aug 16, 2022

Abstract

Improved techniques for thermal imaging and gas detection are provided. In one example, a system includes a first set of filters configured to pass first filtered infrared radiation comprising a first range of thermal wavelengths associated with a background portion of a scene. The system also includes a second set of filters configured to pass second filtered infrared radiation comprising a second range of thermal wavelengths associated with a gas present in the scene. The first and second ranges are independent of each other. The system also includes a sensor array comprising adjacent infrared sensors configured to separately receive the first and second filtered infrared radiation to capture first and second thermal images respectively corresponding to the background portion and the gas. Additional systems and methods are also provided.

First claim

What is claimed is:

1. A system comprising:
a first set of filters configured to pass first filtered infrared radiation comprising a first range of thermal wavelengths associated with a background portion of a scene;
a second set of filters configured to pass second filtered infrared radiation comprising a second range of thermal wavelengths associated with a gas present in the scene, wherein the first and second ranges are independent of each other;
a sensor array comprising adjacent infrared sensors configured to separately receive the first and second filtered infrared radiation to simultaneously capture first and second thermal images respectively corresponding to the background portion and the gas;
a processor configured to:
generate a differential image using the first and second thermal images to distinguish between the gas and the background portion of the scene, and
calibrate the first and second thermal images against each other before the differential image is generated to further distinguish between the gas and the background portion of the scene; and

wherein the first and second filters are arranged in an alternating pattern, the adjacent infrared sensors are configured to separately receive the first and second filtered infrared radiation according to the alternating pattern, and the alternating pattern aligns the first and second thermal images with each other to prevent parallax between the first and second thermal images.

2. The system of claim 1 , wherein:
the alternating pattern is an alternating checkerboard pattern.

3. The system of claim 1 , wherein the first and second ranges are non-overlapping and separated from each other to increase contrast between the gas and the background portion of the scene in the first and second thermal images.

4. The system of claim 1 , wherein the first and second wavelength ranges cause the adjacent infrared sensors to exhibit responses corresponding to a desired range of pixel values of the first and second thermal images.

5. The system of claim 1 , wherein the first and second filters are implemented by one or more substrate layers disposed between the infrared sensors and the scene.

6. The system of claim 1 , wherein the first and second wavelength ranges are selected to permit the adjacent infrared sensors to be operated with identical integration times and capture the first and second thermal images simultaneously.

7. The system of claim 6 , wherein the first and second wavelength ranges are selected to permit the adjacent infrared sensors to be operated with identical gain settings to provide associated pixel values within a desired range for comparison and processing of the first and second thermal images.

8. The system of claim 1 , wherein the processor is configured to:
process the differential image to quantify the gas.

9. The system of claim 8 , wherein the processor is configured to generate a user viewable image using the differential image.

10. The system of claim 9 , further comprising a display component configured to display the user viewable image.

11. A method comprising:
passing, by a first set of filters, first filtered infrared radiation comprising a first range of thermal wavelengths associated with a background portion of a scene;
passing, by a second set of filters, second filtered infrared radiation comprising a second range of thermal wavelengths associated with a gas present in the scene, wherein the first and second ranges are independent of each other;
separately receiving, by adjacent infrared sensors of a sensor array, the first and second filtered infrared radiation;
separately simultaneously capturing, by the adjacent infrared sensors, first and second thermal images respectively corresponding to the background portion and the gas in response to the received first and second filtered infrared radiation;
generating, by a processor, a differential image using the first and second thermal images to distinguish between the gas and the background portion of the scene;
calibrating, by the processor, the first and second thermal images against each other prior to the generating to further distinguish between the gas and the background portion of the scene; and
wherein the first and second filters are arranged in an alternating pattern, the adjacent infrared sensors are configured to separately receive the first and second filtered infrared radiation according to the alternating pattern, and the alternating pattern aligns the first and second thermal images with each other to prevent parallax between the first and second thermal images.

12. The method of claim 11 , wherein:
the alternating pattern is an alternating checkerboard pattern.

13. The method of claim 11 , wherein the first and second ranges are non-overlapping and separated from each other to increase contrast between the gas and the background portion of the scene in the first and second thermal images.

14. The method of claim 11 , wherein:
the simultaneously capturing comprises simultaneously capturing voltages corresponding to pixel values of the first and second thermal images; and
wherein the first and second wavelength ranges cause the pixel values to correspond to a desired range of pixel values.

15. The method of claim 11 , wherein the first and second filters are implemented by one or more substrate layers disposed between the infrared sensors and the scene.

16. The method of claim 11 , wherein the first and second wavelength ranges are selected to permit the adjacent infrared sensors to be operated with identical integration times and capture the first and second thermal images simultaneously.

17. The method of claim 16 , wherein the first and second wavelength ranges are selected to permit the adjacent infrared sensors to be operated with identical gain settings to provide associated pixel values within a desired range for comparison and processing of the first and second thermal images.

18. The method of claim 11 , further comprising:
processing the differential image to quantify the gas.

19. The method of claim 18 , further comprising generating a user viewable image using the differential image.

20. A system configured to perform the method of claim 11 , the system comprising:
the first set of filters;
the second set of filters;
the sensor array; and
the processor.

Assignees

• Flir Systems Ab

Inventors

• Hagman Henning
• Barenthin-Syberg Marta

Classifications

• H04N23/23

  from thermal infrared radiation · CPC title

• G01J5/0014

  for sensing the radiation from gases, flames · CPC title

• G01J3/36

  Investigating two or more bands of a spectrum by separate detectors · CPC title

• G01J5/0802

  Optical filters · CPC title

• G01J2005/106

  Arrays · CPC title