SYSTEM AND METHOD FOR IMAGING OF COATED SUBSTRATES

• US 20070012877A1
• Filed: 08/25/2005
• Published: 01/18/2007
• Est. Priority Date: 08/06/2002
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Don Dimarzio, John Weir, Robert Silberstein
• Inventors: DiMarzio, Don, Silberstein, Robert, Weir, John
• Granted Patent: US 7,193,215 B2
• Time in Patent Office: Days
• US Class Current: 250/341.300
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/8422 Investigating thin films, e.g. matrix isolation method
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination

Abstract

The present invention relates to a system for imaging the surface of a substrate through a coating on the substrate. The system includes an infrared light source positioned to cast an infrared light upon the substrate to thereby create reflected light. A focal plane array may be positioned to receive the reflected light and generate an image therefrom. At least one optical filter may be disposed between the substrate and the focal plane array so as to pass only coating transparent wavelengths of the reflected light along an optical path between the infrared light source and the focal plane array thereby visually revealing irregular structural features of the substrate as at least one image.

Claims

1. A system for imaging the surface of a substrate through a coating on the substrate, comprising:

a) an infrared light source positioned to cast infrared light upon the substrate to thereby create reflected light;

b) a focal plane array positioned to receive the reflected light off the substrate surface and generating an image therefrom; and

c) at least one spectral optical filter disposed between the substrate and the focal plane array so as to pass only coating transparent wavelengths of the reflected light along an optical path between the infrared light source and the focal plane array thereby visually revealing structural features of the substrate as at least one image.

2. The system of claim 1, further comprising a multiplicity of optical filters disposed between the substrate and the focal plane array for generating images a plurality of selected wavelengths and for imaging structural features of the substrate.

3. The system of claim 1, further comprising a multiple imaging device in communication with the focal plane array for simultaneously imaging a plurality of structural features of the substrate.

4. The system of claim 1, further comprising a computer combining and enhancing images generated by the system to thereby generate collective images of selected structural features of the substrate.

5. The system of claim 1, further comprising a computer programmed with substrate patterns for color-coding selected structural features of the substrate within the image based on the substrate patterns so as to provide visual categorization of the structural features.

6. The system of claim 1, further comprising a position sensor for marking reference points on the surface of the substrate so as to store coordinates of structural features on the substrate.

7. The system of claim 1, further comprising a computer comparing images generated at selected wavelengths in a feedback loop so as to automatically enhance image quality of selected structural features of the substrate based upon preselected enhancement criteria.

8. The system of claim 1, where in the light source, the focal plane array and the at least one optical filters are collectively formed within a hand-held device transportable by a single human operator.

9. The system of claim 1, further comprising:

a) a first polarizer disposed between the infrared light source and the substrate for polarizing the infrared light to a first selected polarity; and

b) a second polarizer disposed between the substrate and the focal plane array for polarizing the reflected light to a second selected polarity.

10. The system of claim 9, wherein the first selected polarity and second selected polarity are oppositely configured so as to prevent reflected light corresponding to selected structural features of the substrate from being received upon the focal plane array.

11. The system of claim 9, further comprising a multiplicity of optical filters providing imaging at a plurality of selected wavelengths so as to form an image of a plurality of structure features from the substrate.

12. The system of claim 9, wherein the polarities of the first and second polarizers are rotatable so as to selectably provide a plurality of polarities for imaging structural features from the substrate.

13. The system of claim 9, further comprising a multiple imaging device in communication with the focal plane array for simultaneously imaging a plurality of structural features of the substrate.

14. The system of claim 9, further comprising a computer combining and enhancing images generated by the system to thereby generate collective images of selected structural features of the substrate.

15. The system of claim 9, further comprising a computer programmed with substrate patterns for color-coding selected structural features of the substrate within the image based on the substrate patterns so as to provide visual categorization of the irregular structure features.

16. The system of claim 9, further comprising a position sensor for making reference points on the surface of the substrate so as to store coordinates of structure features of the substrate.

17. The system of claim 9, further comprising a computer comparing images generated at a plurality of selected wavelengths and selected polarities in a feedback loop so as to automatically enhancing the image quality of selected structural features of the substrate based upon selected criteria.

18. The system of claim 9, wherein the infrared light source, the focal plane array and the at least one optical filter are collectively formed within a hand-held device transportable by a single human operator.

19. The system of claim 1, further comprising a communication device for transferring the revealed structure features to a remote human viewable medium.

20. The system of claim 1, further comprising a communication device for transferring the revealed structure features to a database.

31. The system of claim 1, further comprising a communication device for transferring the revealed structural features to a database

21. A method of imaging the surface of a substrate through a coating on the substrate, comprising:

a) directing infrared light upon the substrate;

b) reflecting the infrared light from the substrate to thereby create reflected light;

c) filtering to pass only coating transparent wavelengths of the reflected light;

d) receiving the filtered reflected light on a focal plane array; and

e) generating at least one image from the focal plane array so as to visually reveal structural features of the substrate.

22. The method of claim 21, further comprising comparing a plurality of images generated upon the focal plane array as a function of time to thereby establish a rate of degradation for the substrate.

23. The method of claim 21, further comprising selecting the coating transparent wavelengths from a database storing reflectivity characteristics of coatings found on substrate.

24. The method of claim 21, further comprising comparing the generated images with a pre-selected control image to thereby identify irregular structural features of the substrate.

25. The method of claim 21, further comprising:

a) directing the infrared light through a first polarizer before the infrared light reaches the substrate so as to polarize the infrared light to a first selected polarity; and

b) directing the reflected light through a second polarizer before the infrared light reaches the focal plane array so as to polarize the reflected to a second polarity.

26. The method of claim 25, wherein the first selected polarity and the second polarity are oppositely features of the substrate from being received upon the focal plane.

27. The method of claim 25, further comprising comparing a plurality of images generated upon the focal plane array as a function of time to thereby establish a rate of degradation for the substrate.

28. The method of claim 25, further comprising selecting the selected wavelengths and first and second selected polarities from a database storing reflectivity and characteristics of coatings found on substrates.

29. The method of claim 25, further comprising comparing the generated images with a pre-selected control image to thereby identify irregular structural features of the substrate.

30. The method of claim 21, further comprising transferring the generated images to a remote human viewable medium.