LASER ILLUMINATED GAS IMAGING

• US 20170024871A1
• Filed: 10/03/2016
• Published: 01/26/2017
• Est. Priority Date: 06/20/2014
• Status: Active Grant

• Current Assignee: Fluke Corporation (Fortive Corp.)
• Original Assignee: Fluke Corporation (Fortive Corp.)
• Inventors: Hutton, Derek, Schmidt, Matthew F., Evans, Tyler B.
• Granted Patent: US 10,217,210 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01J 3/0289 Field-of-view determination; Aiming or pointing of a spectrometer; Adjusting alignment; Encoding angular position; Size of measurement area; Position tracking
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01N 2021/3155 Measuring in two spectral ranges, e.g. UV and visible
• CPC Class Codes: G01N 21/3151 using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 21/39 using tunable lasers
• CPC Class Codes: G01N 2201/0221 Portable; cableless; compact; hand-held
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 33/0027 concerning the detector
• CPC Class Codes: G01S 17/00 Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G06T 2207/10048 Infrared image
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: H01L 27/14601 Structural or functional details thereof
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 23/56 provided with illuminating means

Abstract

Aspects of the invention generally relate to illumination gas imaging and detection. Camera systems can illuminate a target scene with light sources configured to emit absorbing and non-absorbing wavelengths with respect to a target gas. An image of the target scene illuminated with a non-absorbing wavelength can be compared to a non-illuminated image of the target scene in order to determine information about the background of the target scene. If sufficient light of the non-absorbing wavelength is scattered by the scene toward a detector, the target scene comprises an adequate background for performing a gas imaging process. A camera system can alert a user of portions of the target scene suitable or unsuitable for performing a gas imaging process. If necessary, the user can reposition the system until sufficient portions of the target scene are recognized as suitable for performing the gas imaging process.

Claims

1. A method for detecting a target gas in a target scene comprising:

capturing a first image of the target scene using a detector element sensitive over a range of wavelengths of light including a first wavelength, the first wavelength being such that the target gas does not significantly absorb light of the first wavelength;

illuminating a first portion of the target scene with light of the first wavelength;

capturing a second image of the target scene, the second image being representative of the target scene illuminated by light of the first wavelength;

comparing corresponding portions of the first image and the second image;

generating a gas detection image in which, for a given one or more pixels in the corresponding portions,

in the condition that the corresponding one or more pixels in the first image and the second image are not sufficiently different, considering such one or more pixels to be inoperable gas detection pixels; and

in the condition that the corresponding one or more pixels in the first image and the second image are sufficiently different, considering such one or more pixels to be operable gas detection pixels; and

displaying the gas detection image in which such pixels considered to be inoperable gas detection pixels are presented in a distinguishing way from such pixels considered to be operable gas detection pixels.

2. The method of claim 1, wherein comparing corresponding portions of the first and second images comprises, for each set of one or more pixels in the corresponding portions of the first and second images, subtracting the one or more pixels in the first image from the corresponding one or more pixels in the second image, defining a first difference value for such one or more pixels.

3. The method of claim 2, wherein determining, for a given one or more pixels, if corresponding one or more pixels in the first and second images are sufficiently different comprises comparing the first difference value for such one or more pixels to a predetermined threshold.

4. The method of claim 1, wherein pixels that are considered to be inoperable gas detection pixels are displayed as a predetermined color in the gas detection image.

5. The method of claim 1, further comprising:

illuminating a second portion of the target scene with light of a second wavelength, the second wavelength being an absorption wavelength of the target gas and the second portion of the target scene at least partially overlapping the first portion; and

capturing a third image of the target scene, the third image being representative of the target scene illuminated by light of the second wavelength; and

wherein

generating the gas detection image comprises, for pixels considered to be operable gas detection pixels, including image data from the captured third image.

6. The method of claim 5, wherein including image data from the third image comprises, for each operable gas detection pixel, determining the difference between image data from the third image and image data from one of (i) the first image and (ii) the second image.

7. The method of claim 6, further comprising receiving a command regarding which of the first and second image data is to be compared to the third image.

8. The method of claim 5, further comprising detecting which of the operable gas detection pixels represent a portion of the target scene comprising the target gas and considering such pixels to be gas pixels.

9. The method of claim 8, wherein displaying the gas detection image further comprises displaying such pixels considered to be gas pixels in a distinguishing way from inoperable gas detection pixels and operable gas detection pixels not considered to be gas pixels.

10. The method of claim 9, further comprising:

pulsing the first and second light sources; and

repeating the method of claim 1 in coordination with pulsing the first and second light sources;

such that

generating and displaying a gas detection image is performed repeatedly in substantially real time.

11. The method of claim 5, wherein the captured first and second, and third images comprise infrared image data, and the first and second wavelengths comprise infrared wavelengths.

12. The method of claim 11, wherein

at least one of the first, second, and third images further comprise visible light image data;

the gas detection image comprises an area comprising infrared image data presented within an area comprising visible light image data; and

the portion of the gas detection image corresponding to the compared corresponding portions of the first and second images is presented within the area comprising infrared image data.

13. The method of claim 12, further comprising displaying pixels considered to be inoperable gas detection pixels in a grayscale visible light image and displaying pixels considered to be operable gas detection pixels in a color visible light image.

14. A portable, hand-held camera system comprising:

a first light source capable of emitting light at a first wavelength, the first wavelength not being an absorption wavelength of a target gas;

a camera module comprising a lens assembly having an associated sensor for detecting images of a target scene, the sensor being sensitive to a range of wavelengths of light including the first wavelength;

a display adapted to display at least a portion of an image; and

a processor;

wherein

the system is configured to

capture an image of a target scene, the image comprising a plurality of pixels;

analyze a plurality of pixels in the image;

determine which of the analyzed plurality of pixels in the image are unsuitable for performing a gas imaging process of the target gas; and

alert a user of the presence of such unsuitable pixels in the image.

15. The system of claim 14, wherein alerting the user comprises displaying an image on the display in which pixels of the image determined to be unsuitable for performing a gas imaging process are visually distinguishable from pixels not determined to be unsuitable for performing a gas imaging process.

16. The system of claim 14, wherein alerting the user comprises playing a sound if one of the (a) number or (b) percentage of the plurality of analyzed pixels determined to be unsuitable for performing a gas imaging process is one of (i) above or (ii) below a predetermined threshold.

17. The system of claim 14, wherein determining which of the analyzed plurality of pixels in the image are unsuitable for performing a gas imaging process comprises:

capturing a first image of the target scene;

illuminating at least a portion of the target scene with light of the first wavelength via the first light source;

capturing a second image of the target scene while illuminating at least a portion of the target scene with the first light source;

comparing, pixel by pixel, corresponding portions of the first image and the second image; and

for a given pixel, in the condition that the such pixel in the first image is not sufficiently different from the corresponding pixel in the second image, considering such pixel unsuitable for performing a gas imaging process.

18. The system of claim 17, further configured to detect which of the plurality of compared pixels not determined unsuitable for performing a gas imaging process is representative of the target gas in the target scene.

19. The system of claim 18, further comprising a second light source configured to emit light of a second wavelength, the second wavelength being an absorption wavelength of the target gas.