Portable evaluation of window transmission

• US 7,880,885 B1
• Filed: 11/13/2008
• Issued: 02/01/2011
• Est. Priority Date: 11/13/2008
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Stana, James M., Williams, Kevin F., Gilmore, Ronald H.
• Primary Examiner(s): Toatley; Gregory J
• Assistant Examiner(s): Underwood; Jarreas C
• Application Number:
  US12/270,611
• Time in Patent Office: 810 Days
• Field of Search: 3562371-2416, 3562421-2438, 356426-431, 356600-640
• US Class Current: 356/432
• CPC Class Codes: G01N 2021/5915 Processing scan data in densitometry
• CPC Class Codes: G01N 2021/5957 using an image detector type detector, e.g. CCD
• CPC Class Codes: G01N 2021/9586 Windscreens
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 21/958 Inspecting transparent materials or objects, e.g. windscreens for conveyed flat sheet or rod G01N21/896
• CPC Class Codes: G01N 2201/0221 Portable; cableless; compact; hand-held

Abstract

An apparatus and method for evaluating window transmission loss comprising taking a plurality of photographs through a filter of a window to be evaluated, determining a percentage of the window shown in each photograph that is undamaged, and computing an estimate of transmission loss for the window from the percentages determined.

Claims

1. A method for evaluating aircraft window transmission loss, the method comprising the steps of:

taking a plurality of photographs through a filter of an aircraft window to be evaluated;

determining a percentage of the window shown in each photograph that is undamaged; and

computing an estimate of transmission loss for the window from the percentages determined.

2. The method of claim 1 wherein the taking step comprises taking the plurality of photographs through a filter and a prism.

3. The method of claim 2 wherein the taking step comprises taking the plurality of photographs through a filter and a Wollistan prism.

4. The method of claim 1 additionally comprising the step of illuminating the window.

5. The method of claim 4 wherein the illuminating step comprises illuminating the window using a light passed through a polarizing filter.

6. The method of claim 1 wherein the computing step comprises averaging the determined percentages.

7. The method of claim 6 wherein the computing step comprises adding a transmission loss of an original sample window to a slope multiplied by the computed average.

8. The method of claim 1 wherein the method is conducted using a portable device.

9. The method of claim 1 wherein the taking step comprises taking magnified photographs.

10. The method of claim 9 wherein the taking step comprises taking magnified photographs at a magnification of at least about 100×

.

11. The method of claim 1 wherein the determining step comprises comparing intensity values of individual pixels against expected values for an undamaged window.

12. An apparatus for evaluating aircraft window transmission loss, said apparatus comprising:

a filter through which a camera takes a plurality of photographs of an aircraft window to be evaluated; and

a processing unit determining a percentage of the window shown in each photograph that is undamaged and computing an estimate of transmission loss for the window from the percentages determined.

13. The apparatus of claim 12 additionally comprising a prism through which the plurality of photographs is taken.

14. The apparatus of claim 13 wherein said prism is a Wollistan prism.

15. The apparatus of claim 12 additionally comprising a light source illuminating the window.

16. The apparatus of claim 15 additionally comprising a polarizing filter through which light from said light source passes before illuminating the window.

17. The apparatus of claim 12 wherein said processing unit averages the determined percentages.

18. The apparatus of claim 17 wherein said processing unit adds a transmission loss of an original sample window to a slope multiplied by the computed average.

19. The apparatus of claim 12 wherein said apparatus is portable.

20. The apparatus of claim 12 additionally comprising a magnifying device through which the photographs are taken.

21. The apparatus of claim 20 wherein said magnifying device magnifies at least about 100×

.

22. The apparatus of claim 12 wherein said processing unit compares intensity values of individual pixels against expected values for an undamaged window.