Non-destructive testing and imaging

• US 20050264796A1
• Filed: 02/25/2005
• Published: 12/01/2005
• Est. Priority Date: 09/10/2003
• Status: Active Grant

• Current Assignee: Raven Engineering, Inc.
• Original Assignee: Shearographics, LLC
• Inventors: Shaw, Eugene L., Malkan, David D., Wright, Forrest S.
• Granted Patent: US 7,436,504 B2
• Time in Patent Office: Days
• US Class Current: 356/237.200
• CPC Class Codes: G01B 11/162 by speckle- or shearing interferometry
• CPC Class Codes: G01M 17/027 using light, e.g. infrared, ultraviolet or holographic techniques
• CPC Class Codes: G01N 2021/8887 based on image processing techniques
• CPC Class Codes: G01N 2021/9548 Scanning the interior of a cylinder
• CPC Class Codes: G01N 21/8851 Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002
• CPC Class Codes: G01N 21/954 Inspecting the inner surface of hollow bodies, e.g. bores

Abstract

A method of non-destructive testing includes non-destructively testing an object over a range of test levels, directing coherent light onto the object, directly receiving the coherent light substantially as reflected straight from the object, and capturing the reflected coherent light over the range of test levels as a plurality of digital images of the object. The method also includes calculating differences between pixel values of a plurality of pairs of digital images of the plurality of digital images, and adding the pixel value differences of the plurality of pairs of digital images to yield at least one cumulative differential image.

Claims

1. A method of non-destructive testing comprising:

non-destructively testing an object over a range of test levels;

directing coherent light onto the object;

directly receiving the coherent light substantially as reflected straight from the object;

capturing the reflected coherent light over the range of test levels as a plurality of digital images of the object;

calculating differences between pixel values of a plurality of pairs of digital images of the plurality of digital images; and

adding the pixel value differences of the plurality of pairs of digital images to yield at least one cumulative differential image.

2. The method of claim 1 wherein the capturing step includes capturing the plurality of digital images of the object at predefined test levels of the range of test levels.

3. The method of claim 1 wherein the capturing step includes capturing the plurality of digital images of the object at at least two different test levels over the range of test levels.

4. The method of claim 1 wherein the calculating step includes calculating differences between pixel values of a first pair of at least two pairs of digital images and of a second pair of at least two pairs of digital images wherein the first and second pairs have a digital image in common.

5. The method of claim 1 wherein the calculating step includes calculating differences between pixel values of a first pair of at least two pairs of digital images and of a second pair of at least two pairs of digital images wherein the first pair has first and second digital images and the second pair has third and fourth digital images, such that the first and second pairs have no digital images in common.

6. The method of claim 1 wherein the calculating step includes:

calculating differences between pixel values of first, second, and third pairs of at least three pairs of digital images;

adding the differences of the first and second pairs of the at least three pairs of digital images to yield a first cumulative differential image; and

adding pixel values of the first cumulative differential image to the differences of the third pair of the at least three pairs of digital images to yield at least one more cumulative differential image.

7. The method of claim 1 further comprising:

the capturing step including capturing the plurality of digital images of the object at predefined test levels of the range of test levels;

calculating differences between pixel values of a first, second, and third pairs of at least three pairs of digital images, wherein the first pair has first and second digital images, the second pair has third and fourth digital images, and the third pair have fifth and sixth digital images, such that the first, second, and third pairs have no digital images in common;

adding the differences of the first and second pairs of the at least three pairs of digital images to yield a first cumulative differential image; and

adding pixel values of the first cumulative differential image to the differences of the third pair of the at least three pairs of digital images to yield at least one more cumulative differential image.

8. The method of claim 1 further comprising:

brightening the at least one cumulative differential image; and

smoothing the at least one cumulative differential image.

9. The method of claim 1 further comprising:

inverting the at least one cumulative differential image to yield at least one inverted image;

topographically filtering the at least one inverted image to yield at least one topographically filtered image; and

segment filtering the at least one topographically filtered image to yield at least one enhanced image.

10. The method of claim 9 further comprising:

quantifying anomalies in the at least one enhanced image to yield at least one analyzed image.

11. The method of claim 10 wherein the quantifying step includes:

applying at least one of an anomaly counter and an anomaly finder process to the at least one enhanced image to yield at least one analyzed image.

12. The method of claim 1 wherein at further comprising:

topographically filtering the at least one cumulative differential image to yield at least one topographically filtered image;

segment filtering the at least one topographically filtered image to yield at least one enhanced image;

quantifying anomalies in the at least one enhanced image to yield at least one analyzed image; and

digitally overlaying at least one of the at least one analyzed image and the at least one enhanced image on a baseline image of the plurality of images.

13. A product processed according to the method of claim 1.

14. The method of claim 1 wherein the capturing step includes discretely capturing the reflected coherent light at two test levels over the range of test levels as two digital images.

15. The method of claim 1 wherein the directly receiving step includes receiving the coherent light that has neither passed through a birefringent or shearing optic material nor has been reflected from a beam splitter.

16. The method of claim 1 wherein the non-destructive testing step includes continuously progressively stressing the object to expose the object to continuously progressive levels of deformation.

17. A computer-readable medium carrying instructions for enabling at least one processor to perform method steps of non-destructive testing, the method comprising:

calculating differences between pixel values of a plurality of pairs of digital images captured as coherent light directly received substantially as reflected straight from an object undergoing non-destructive testing over a range of test levels;

adding the pixel value differences of the plurality of pairs of digital images to yield at least one cumulative differential image.

18. The computer-readable medium of claim 17, wherein the method further comprises the calculating step further including calculating differences between pixel values of a first pair of at least two pairs of digital images and of a second pair of at least two pairs of digital images wherein the first and second pairs have a digital image in common.

19. The computer-readable medium of claim 17, wherein the method further comprises the calculating step further including calculating differences between pixel values of a first pair of at least two pairs of digital images and of a second pair of at least two pairs of digital images wherein the first pair has first and second digital images and the second pair has third and fourth digital images, such that the first and second pairs have no digital images in common.

20. The computer-readable medium of claim 17, wherein the method further comprises the calculating step further including:

calculating differences between pixel values of a first, second, and third pairs of at least three pairs of digital images;

adding the differences of the first and second pairs of the at least three pairs of digital images to yield a first cumulative differential image; and

adding pixel values of the first cumulative differential image to the differences of the third pair of the at least three pairs of digital images to yield at least one more cumulative differential image.

21. The computer-readable medium of claim 17, wherein the method further comprises:

the capturing step including capturing the plurality of digital images of the object at predefined test levels of the range of test levels;

calculating differences between pixel values of a first, second, and third pairs of at least three pairs of digital images, wherein the first pair has first and second digital images, the second pair has third and fourth digital images, and the third pair have fifth and sixth digital images, such that the first, second, and third pairs have no digital images in common;

adding the differences of the first and second pairs of the at least three pairs of digital images to yield a first cumulative differential image; and

adding pixel values of the first cumulative differential image to the differences of the third pair of the at least three pairs of digital images to yield at least one more cumulative differential image.

22. The computer-readable medium of claim 17, wherein the method further comprises:

brightening the at least one cumulative differential image; and

smoothing the at least one cumulative differential image.

23. The computer-readable medium of claim 17, wherein the method further comprises:

inverting the at least one cumulative differential image to yield at least one inverted image;

topographically filtering the at least one inverted image to yield at least one topographically filtered image; and

segment filtering the at least one topographically filtered image to yield at least one enhanced image.

24. The computer-readable medium of claim 23, wherein the method further comprises:

quantifying anomalies in the at least one enhanced image to yield at least one analyzed image.

25. The computer-readable medium of claim 24, wherein the method further comprises the quantifying step including applying at least one of an anomaly counter and an anomaly finder process to the at least one enhanced image to yield at least one analyzed image.

26. The computer-readable medium of claim 17 wherein the method further comprises:

topographically filtering the at least one cumulative differential image to yield at least one topographically filtered image;

segment filtering the at least one topographically filtered image to yield at least one enhanced image;

quantifying anomalies in the at least one enhanced image to yield at least one analyzed image; and

digitally overlaying at least one of the at least one analyzed image and the at least one enhanced image on a baseline image of the plurality of images.

27. The computer-readable medium of claim 17, wherein the method further comprises at least one of the following steps:

a) simultaneously displaying a plurality of test sets each including at least one image of the object; and

b) displaying a print preview of at least one test set each including a plurality of images and to accept at least one of a title for the at least one test set and a description for each of the plurality of images.

28. The computer-readable medium of claim 17, wherein the method further comprises at least one of the following steps:

a) displaying live images captured by imaging equipment and to accept user input for at least one of the following characteristics of the imaging equipment;

gain, exposure, brightness, contrast, and gamma;

b) accepting user input for at least one of the following characteristics of the imaging equipment;

camera vertical position, camera horizontal position, and camera tilt.

29. A method of creating a database of information from a non-destructive testing process of a plurality of objects, wherein the method comprises:

creating at least one database record for each of the plurality of objects, the at least one database record including the following information;

at least one object identifier;

at least one reference to at least one digital image; and

at least one anomaly characteristic including at least one of anomaly quantity and anomaly size; and

storing the at least one database record for subsequent access.

30. The database created by the method of claim 29.

31. The method of claim 29 further comprising:

accessing a stored record of the at least one database record; and

printing the stored record.

32. A machine readable output of a database record created by the method of claim 31.

33. The method of claim 29 wherein the at least one anomaly characteristic of anomaly size includes at least one of a measurement of anomaly height, anomaly width, and anomaly area, wherein the measurement is in at least one of pixels, millimeters, and inches.

34. The method of claim 29 wherein the at least one database record further includes at least one of the following data:

a) imaging data including at least one of light source type, light source power level, light source position, focus setting, focal length, exposure time, filter setting, and iris setting;

b) test level data including at least one of a minimum test level and a maximum test level;

c) test environment data including at least one of temperature, humidity, and settling time;

d) test object data including at least one of manufacturer, model, size, used vs. new indication, cleanliness rating, stiffness rating;

e) test result data including at least one of test date, test time, quantity of anomalies, size of largest anomaly including at least one of height, weight, and area, size of smallest anomaly including at least one of height, weight, and area; and

f) general data including at least one of an indication of test purpose, customer name, customer number, unique test object identification, operator name, and an indication of the area of the object tested.

35. A method of detecting an anomaly in an object comprising:

providing a source of coherent light;

shining the light directly onto the object surface, thereby generating a reflected light from the object;

stressing the object over a range of test levels;

providing a reflected light receiving apparatus for receiving the light reflected directly from the tire when the object is in a stressed and unstressed condition;

capturing the reflected light over the range of test levels as a plurality of digital images of the object;

calculating differences between pixel values of a plurality of pairs of digital images of the plurality of digital images;

adding the pixel value differences of the plurality of pairs of digital images to yield at least one cumulative differential image;

providing a processor which views and compares images of reflected light from the reflected light receiving apparatus when the object is stressed and unstressed thereby ascertaining an anomaly in the object and generates an output from the comparison; and

displaying, from apparatus electronically connected to the processor, the output from the processor.

36. An anomaly detector apparatus for detecting an anomaly in an object comprising:

a source of coherent light to shine the light directly onto the object surface with the light being reflected from the object;

a stressing apparatus, which can stress the object over a range of test levels;

a reflected light receiving apparatus for receiving the light reflected directly from the object when the object is in a stressed and unstressed condition;

a processor, which compares images of reflected light from the reflected light receiving apparatus when the object is stressed and unstressed thereby ascertaining an anomaly in the object and which generates an output from the comparison, the processor being adapted to;

capture the reflected light over the range of test levels as a plurality of digital images of the object;

calculate differences between pixel values of a plurality of pairs of digital images of the plurality of digital images; and

add the pixel value differences of the plurality of pairs of digital images to yield at least one cumulative differential image; and

a display apparatus electronically connected to the processor for displaying the output from the processor.

37. A non-destructive testing system comprising:

a non-destructive testing apparatus to test an object over a range of test levels;

a light source to direct coherent light onto the object;

an imaging device to directly receive light substantially as reflected straight from the object and thereby capture a plurality of digital images of the object over the range of test levels;

a memory for storing the plurality of digital images and for storing a computer-executable program;

an input device for receiving input from an operator;

an output device for transmitting output to the operator;

a processor in communication with the imaging device, the memory, and the input and output devices, the processor being adapted to;

execute the computer-executable program to store the plurality of images in the memory,

calculate differences between pixel values of a plurality of pairs of digital images of the plurality of digital images, and

add the pixel value differences of the plurality of pairs of digital images to yield at least one cumulative differential image.