Range gated shearography systems and related methods

• US 7,667,824 B1
• Filed: 02/05/2008
• Issued: 02/23/2010
• Est. Priority Date: 02/06/2007
• Status: Expired due to Fees

• Current Assignee: Alpha Technology, LLC
• Original Assignee: Alpha Technology, LLC
• Inventors: Moran, Steven E.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Ratcliffe; Luke D
• Application Number:
  US12/026,511
• Time in Patent Office: 749 Days
• Field of Search: 356 301- 22
• US Class Current: 356/5.03
• CPC Class Codes: G01B 11/2441 using interferometry
• CPC Class Codes: G01B 2290/45 Multiple detectors for detecting interferometer signals
• CPC Class Codes: G01B 9/02098 Shearing interferometers
• CPC Class Codes: G01S 17/18 wherein range gates are used

Abstract

A range-gated shearography system and related methods. Implementations of range-gated shearography systems may include a laser light source, at least one imaging detector coupled to the laser light source, a shearing interferometer coupled to the at least one imaging detector, and a ranging detector coupled to the laser light source. A method of range-gating a shearography system may include emitting laser light, determining a range interval for at least one object, receiving reflected laser light from the at least one object through a shearing interferometer from the range interval, and collecting at least one shearography image.

Claims

1. A range gated shearography system comprising:

a laser light source;

at least one imaging detector coupled to the laser light source;

a shearing interferometer coupled to the at least one imaging detector; and

a ranging detector coupled to the laser light source.

2. The system of claim 1, wherein the at least one imaging detector is selected from the group consisting of multiplier phototubes, avalanche photodiodes, a streak tube detector, microchannel plate intensified charge coupled devices, a read-out integrated circuit array, a charge coupled detector, a proximity-focused detector, a high-bandwidth detector, an intensified imaging detector, an unintensified imaging detector, and an SM3D detector.

3. The system of claim 1, wherein the ranging detector is selected from the group consisting of multiplier phototubes, avalanche photodiodes, a streak tube detector, microchannel plate intensified charge coupled devices, a read-out integrated circuit array, a charge coupled detector, a proximity-focused detector, a high-bandwidth detector, an intensified imaging detector, an unintensified imaging detector, and an SM3D detector.

4. The system of claim 1, wherein the shearing interferometer comprises a shearing wedge.

5. The system of claim 1, wherein the shearing interferometer comprises a Michelson interferometer.

6. The system of claim 5, wherein a second imaging detector is coupled to the Michelson interferometer.

7. The system of claim 1, further comprising a video processor coupled to the imaging detector.

8. A method of range-gating a shearography system comprising:

emitting laser light;

determining a range interval for at least one object;

receiving reflected laser light from the at least one object through a shearing interferometer from the range interval; and

collecting at least one shearography image.

9. The method of claim 8, wherein the range interval is a DOF region for at least one imaging detector.

10. The method of claim 8, wherein determining a range interval further comprises measuring the range to the at least one object using a ranging detector coupled with a time-of-flight computer.

11. The method of claim 10, wherein the ranging detector is selected from the group consisting of multiplier phototubes, avalanche photodiodes, a streak tube detector, microchannel plate intensified charge coupled devices, a read-out integrated circuit array, a charge coupled detector, a proximity-focused detector, a high-bandwidth detector, an intensified imaging detector, an unintensified imaging detector, and an SM3D detector.

12. The method of claim 9, wherein the at least one imaging detector is selected from the group consisting of multiplier phototubes, avalanche photodiodes, a streak tube detector, microchannel plate intensified charge coupled devices, a read-out integrated circuit array, a charge coupled detector, a proximity-focused detector, a high-bandwidth detector, an unintensified imaging detector, and an SM3D detector.

13. The method of claim 9, further comprising intensifying the received reflected laser light.

14. The method of claim 8, wherein emitting laser light further comprises emitting pulses of laser light.

15. A method of range-gating a shearography system comprising:

emitting laser light;

receiving reflected laser light from at least one object with a ranging detector;

determining a range to the at least one object;

transmitting the range to at least one imaging detector;

receiving reflected laser light from the at least one object with the at least one imaging detector through a shearing interferometer and collecting at least one shearography image;

processing the at least one shearography image with a video processor.

16. The method of claim 15, wherein the at least one imaging detector is selected from the group consisting of multiplier phototubes, avalanche photodiodes, a streak tube detector, microchannel plate intensified charge coupled devices, a read-out integrated circuit array, a charge coupled detector, a proximity-focused detector, a high-bandwidth detector, an unintensified imaging detector, and an SM3D detector.

17. The method of claim 15, wherein the ranging detector is selected from the group consisting of multiplier phototubes, avalanche photodiodes, a streak tube detector, microchannel plate intensified charge coupled devices, a read-out integrated circuit array, a charge coupled detector, a proximity-focused detector, a high-bandwidth detector, an intensified imaging detector, an unintensified imaging detector, and an SM3D detector.

18. The method of claim 15, further comprising intensifying the received reflected laser light.

19. The method of claim 15, wherein emitting laser light further comprises emitting pulses of laser light.

20. The method of claim 15, wherein receiving reflected laser light from the at least one object further comprises range-gating the at least one imaging detector to receive reflected laser light from the at least one object within a DOF region determined using the range to the at least one object.