Laser bond inspection with compact surface motion sensor

• US 9,857,288 B2
• Filed: 11/01/2014
• Issued: 01/02/2018
• Est. Priority Date: 11/01/2013
• Status: Active Grant

• Current Assignee: LSP Technologies Incorporated
• Original Assignee: LSP Technologies Incorporated
• Inventors: Sokol, David, Walters, Craig
• Primary Examiner(s): LaBalle, Clayton E
• Assistant Examiner(s): BUTLER, KEVIN C
• Application Number:
  US14/530,745
• Publication Number:
  US 20150122046A1
• Time in Patent Office: 1,158 Days
• Field of Search: 73800
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge
• CPC Class Codes: G01B 11/18 using photoelastic elements
• CPC Class Codes: G01L 1/24 by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
• CPC Class Codes: G01L 1/242 the material being an optical fibre
• CPC Class Codes: G01N 19/04 Measuring adhesive force between materials, e.g. of sealing tape, of coating
• CPC Class Codes: G01N 2203/005 Electromagnetic means
• CPC Class Codes: G01N 2203/0055 using mechanical waves, e.g. acoustic
• CPC Class Codes: G01N 29/2412 using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: G01N 3/068 with optical indicating or recording means

Abstract

Methods, systems, and apparatuses are disclosed for laser bond inspection of an angled or compact bonded article.

Claims

1. A system for laser bond inspection of a bond in an article, the system comprising:

a laser to provide a pulsed laser beam;

a laser beam delivery system to deliver the pulsed laser beam to an inspection head;

the inspection head to deliver the pulsed laser beam to the article, wherein the inspection head is oriented at an acute angle with respect to normal to a surface of the article, wherein the inspection head comprises;

a first output to generate a transparent overlay for the laser bond inspection of the bond in the article;

a second output to deliver the pulsed laser beam to the surface of the article; and

a surface motion sensor to detect surface motion in the article in response to delivering the pulsed laser beam to the surface of the article, wherein the surface motion sensor is further to generate one or more signals in response to detecting the surface motion.

2. The system of claim 1, wherein the laser is to provide a pulsed laser beam having:

a pulse energy between about 3-50 Joules per pulse;

a pulse width of about 70-300 nanoseconds (ns); and

a beam diameter of about 5-12 millimeters (mm) at the surface of the bonded article; and

wherein the laser is further to provide laser beam pulses in a low-high-low pulse energy sequence to cause stress waves through the bond of the article.

3. The system of claim 1, wherein the laser beam delivery system comprises one or more mirrors.

4. The system of claim 1, wherein the laser beam delivery system comprises an articulated arm attached to the inspection head.

5. The system of claim 1, wherein the laser beam delivery system comprises an optical fiber.

6. The system of claim 1, wherein the acute angle is one of about 50 degrees (°

) and between 0°

to 50 degrees relative to the normal to the surface of the article.

7. The system of claim 1, wherein the compact surface motion sensor comprises an off-axis electromagnetic acoustic transducer (EMAT) for detecting the surface motion at a location off-axis from a laser beam impact area associated with the pulsed laser beam.

8. The system of claim 1, wherein the surface motion sensor comprises an optical interferometer.

9. The system of claim 8, wherein the optical interferometer comprises an optical fiber to deliver a continuous wave laser to detect surface motion on the article.

10. A system comprising:

a laser to provide a pulsed laser beam for laser bond inspection of a bond in an article;

a laser beam delivery system to deliver the pulsed laser beam to an inspection head, wherein the inspection head comprises;

a first output to generate a transparent overlay for the laser bond inspection of the bond in the article;

a second output to deliver the pulsed laser beam to the surface of the article; and

a surface motion sensor to detect surface motion in the article in response to delivering the pulsed laser beam to the surface of the article, wherein the surface motion sensor is further to generate one or more signals in response to detecting the surface motion.

11. The system of claim 10, wherein the inspection head is oriented at an acute angle with respect to normal to a surface of the article.

12. The system of claim 11, wherein generating the one or more signals in response to detecting the surface motion comprises generating one or more signals characterizing the detected surface motion.

13. The system of claim 12, wherein the acute angle is one of about 50 degrees (°

) and between 0°

to 50 degrees relative to the normal to the surface of the article.

14. The system of claim 13,

wherein the article comprises a plurality of bonds;

and

wherein a given bond of the plurality of bonds is orientated at an acute bond angle with respect to the normal to the surface of the article; and

wherein the inspection head is oriented relative to the normal to the surface of the article for laser bond inspection of the given bond in the article.

15. The system of claim 14, wherein the laser beam delivery system corresponds to one of an articulated arm and/or a fiber optic, and the inspection head corresponds to an angled inspection head.

16. The system of claim 13, wherein the acute bond angle is between 0°

to 50 degrees relative to the normal to the surface of the article.

17. The system of claim 16, wherein the pulsed laser beam comprises:

a pulse energy between about 3-50 Joules per pulse;

a pulse width of about 70-300 nanoseconds (ns); and

a beam diameter of about 5-12 millimeters (mm) at the surface of the article.

18. The system of claim 16, wherein the laser is further to provide laser beam pulses in a low-high-low pulse energy sequence to cause stress waves through the bond of the article.