System and method for detecting optical defects in transparencies

• US 8,917,312 B1
• Filed: 02/26/2009
• Issued: 12/23/2014
• Est. Priority Date: 02/26/2009
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Gleason, Michael P., Thomas, Matthew M., Pulcher, Daniel E., Reed, Douglas E., Roberts, Anthony C.
• Primary Examiner(s): Vo, Tung
• Assistant Examiner(s): SOSANYA, OBAFEMI OLUDAYO
• Application Number:
  US12/394,012
• Time in Patent Office: 2,126 Days
• Field of Search: 349/61, 349/112, 356/239.1, 362/471, 362/511
• US Class Current: 348/36
• CPC Class Codes: G01N 2021/9586 Windscreens
• CPC Class Codes: G01N 21/958 Inspecting transparent materials or objects, e.g. windscreens for conveyed flat sheet or rod G01N21/896

Abstract

An optical defect detection system is provided for recording an image of a transparency for detecting optical defects therein. The transparency may be formed with a contour. The defect detection system may comprise a light source, a diffuser and an image recording device for recording images of the transparency. The light source is configured to emit light and may be positioned adjacent one of the sides of the transparency. The image recording device may be positioned on a side of the transparency opposite the diffuser. The diffuser may be contoured complementary to the contour of the transparency and may be positioned between the light source and the transparency.

Claims

1. An optical defect detection system for recording an image of a transparency having a contour, comprising:

a plurality of lighting elements configured to emit light and arranged in an arcuate cross-sectional profile substantially similar to the transparency cross-sectional profile, each one of the lighting elements having a tubular shape and extending in a lengthwise direction along a length of the transparency, the plurality of lighting elements being arranged in an arcuate pattern;

a diffuser interposed between the lighting elements and the transparency and being a physically separate component from the lighting elements and the transparency and providing a background for recording images of the transparency;

the diffuser having an arcuate cross-sectional profile being substantially similar to the transparency cross-sectional profile;

the arcuate cross-sectional profile of the diffuser and the light source being configured such that the transparency is substantially uniformly backlit by the combination of the lighting elements and the diffuser;

a reflector positioned on a side of the lighting elements opposite the diffuser and being configured to reflect light emitted by the lighting elements toward the diffuser; and

an image recording device positioned on a side of the transparency opposite the diffuser such that no intervening elements are located between the image recording device and the transparency, the image recording device being configured to record the image of the substantially uniformly backlit transparency for detection of optical defects in the transparency.

2. The defect detection system of claim 1 wherein:

the transparency having a viewing portion;

the image recording device, the transparency and the diffuser being configured such that a vector that extends from the image recording device and which passes through any point on the viewing portion will intersect the diffuser.

3. The defect detection system of claim 1 wherein:

the transparency has a viewing portion defining upper and lower edges;

the image recording device having a vertical field of view encompassing the upper and lower edges.

4. The defect detection system of claim 1 wherein:

the transparency has a viewing portion defining opposing lateral edges;

the image recording device being configured as a panoramic camera rotatable about an axis of rotation to record the viewing portion between and including the opposing lateral edges.

5. The defect detection system of claim 1 wherein:

the image recording device is configured to record optical defects having a width at least as small as about 0.010 inch.

6. The defect detection system of claim 1 wherein:

the diffuser is configured to transmit at least about 50% of the light emitted by the lighting elements.

7. The defect detection system of claim 1 wherein:

the image recording device comprises at least one of the following;

a digital camera, a video camera.

8. The defect detection system of claim 1 wherein:

the transparency comprises at least one of an aircraft canopy and an aircraft windshield.

9. An optical defect detection system for recording an image of a transparency having a viewing portion with opposing lateral edges, the detection system comprising:

a plurality of lighting elements configured to emit light and arranged in an arcuate cross-sectional profile substantially similar to the transparency cross-sectional profile, each one of the lighting elements having a tubular shape and extending in a lengthwise direction along a length of the transparency, the plurality of lighting elements being arranged in an arcuate pattern;

a diffuser interposed between the lighting elements and the transparency and being a physically separate component from the lighting elements and the transparency and providing a background for recording images of the transparency;

the diffuser having an arcuate cross-sectional profile being substantially similar to the transparency cross-sectional profile;

the arcuate cross-sectional profile of the diffuser and the lighting elements being configured such that the transparency is substantially uniformly backlit by the combination of the lighting elements and the diffuser;

a reflector positioned on a side of the lighting elements opposite the diffuser and being configured to reflect light emitted by the lighting elements toward the diffuser; and

an image recording device positioned on a side of the transparency opposite the diffuser such that no intervening elements are located between the image recording device and the transparency, the image recording device being rotatable about an axis of rotation to record a horizontal field of view encompassing the viewing portion between and including the opposing lateral edges;

the image recording device, the transparency and the diffuser being configured such that a vector extending from the image recording device and passing through any point on the viewing portion intersects the diffuser;

the image recording device being configured to record the image of the substantially uniformly backlit transparency for detection of optical defects in the transparency.

10. The defect detection system of claim 9 wherein:

the transparency has a viewing portion defining upper and lower edges;

the image recording device having a vertical field of view encompassing the upper and lower edges.

11. The defect detection system of claim 9 wherein:

the image recording device is configured to record optical defects having a width at least as small as about 0.010 inch.

12. The defect detection system of claim 9 wherein:

the diffuser is configured to transmit at least about 50% of the light emitted by the lighting elements.

13. The defect detection system of claim 9 wherein:

the image recording device comprises at least one of the following;

a digital camera, a video camera.

14. A method of detecting optical defects in a transparency having a viewing portion, the method comprising the steps of:

positioning a plurality of lighting elements adjacent the transparency, the lighting elements being arranged in an arcuate cross-sectional profile substantially similar to the transparency cross-sectional profile, each one of the lighting elements having a tubular shape and extending in a lengthwise direction along a length of the transparency, the plurality of lighting elements being arranged in an arcuate pattern;

emitting light from the lighting elements;

diffusing the light onto a diffuser for substantially uniformly backlighting the transparency, the diffuser being a physically separate component from the lighting elements and the transparency and providing a background for recording images of the transparency, the diffuser having an arcuate cross-sectional profile being substantially similar to the transparency cross-sectional profile, the arcuate cross-sectional profile of the diffuser and the lighting elements being configured such that the transparency is substantially uniformly backlit by the combination of the lighting elements and the diffuser;

reflecting the light toward the diffuser using a reflector positioned on a side of the lighting elements opposite the diffuser;

positioning an image recording device on a side of the transparency opposite the diffuser such that no intervening elements are located between the image recording device and the transparency and such that a vector that extends from the image recording device and which passes through any location on the transparency will intersect the diffuser; and

recording an image of the substantially uniformly backlit transparency for detection of optical defects in the transparency.

15. The method of claim 14 further comprising the step of:

moving the image recording device while recording the image of the viewing portion.

16. The method of claim 15 wherein the step of moving the image recording device comprises:

rotating the image recording device about at least one axis of rotation while recording the image of the viewing portion.

17. The method of claim 16 wherein:

the axis of rotation is a vertical axis of rotation.

18. The method of claim 14 further comprising the step of:

transmitting at least about 50% of the light through the diffuser.

19. The method of claim 14 further comprising the step of:

positioning the image recording device approximately midway along a height of the transparency.

20. The method of claim 14 further comprising the step of:

recording optical defects having a width at least as small as about 0.010 inch.