Defect detection method and defect detection device

Patent metadata

Field	Value
Publication number	US-10429172-B2
Application number	US-201816004966-A
Country	US
Kind code	B2
Filing date	Jun 11, 2018
Priority date	Jun 12, 2017
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

A defect detection method includes the following processes: a) stroboscopically illuminating the entire surface of an object within an examination area of the object while inducing a first elastic wave across the examination area on the object, and controlling the phase of the elastic wave and the timing of the stroboscopic illumination to collectively measure a back-and-forth displacement of each point within the examination area in at least three phases of the elastic wave; b) identifying a surface location which is the location of a defect on the examination area, based on the back-and-forth displacement of each point within the examination area in the at least three different phases; and c) injecting a second elastic wave into a region inside the surface location from a limited area including the surface location, and determining the location and/or size in the depth direction of the defect, based on a response wave.

First claim

The invention claimed is:

1. A defect detection method, comprising:
a) a collective displacement measurement process including: performing stroboscopic illumination on an entire surface of an object to be examined within an examination area of the object while inducing a first elastic wave across the entire examination area on the object; and controlling a phase of the elastic wave and a timing of the stroboscopic illumination to collectively measure a displacement in a back-and-forth direction of each point within the examination area in at least three mutually different phases of the elastic wave;
b) a defect location identification process including: identifying a location of a defect on a surface of the examination area, based on the displacement in the back-and-forth direction of each point within the examination area in the at least three different phases; and
c) a depth direction information acquisition process including: injecting a second elastic wave into a region inside of the object at the location from a limited area on the surface including the location of the defect on the surface; and determining a location and/or size in the depth direction of the defect, based on a response wave of the second elastic wave.

2. The defect detection method according to claim 1 , wherein the second elastic wave has a higher frequency than a frequency of the first elastic wave.

3. The defect detection method according to claim 1 , wherein two or three of operations of inducing the first elastic wave, injecting the second elastic wave and detecting the response wave are performed with a common transducer.

4. The defect detection method according to claim 2 , wherein two or three of operations of inducing the first elastic wave, injecting the second elastic wave and detecting the response wave are performed with a common transducer.

5. The defect detection method according to claim 1 , wherein both induction of the first elastic wave and injection of the second elastic wave are performed with a common oscillation circuit.

6. The defect detection method according to claim 2 , wherein both induction of the first elastic wave and injection of the second elastic wave are performed with a common oscillation circuit.

7. The defect detection method according to claim 3 , wherein both induction of the first elastic wave and injection of the second elastic wave are performed with a common oscillation circuit.

8. The defect detection method according to claim 4 , wherein both induction of the first elastic wave and injection of the second elastic wave are performed with a common oscillation circuit.

9. The defect detection method according to claim 1 , wherein the displacement in the back-and-forth direction of each point within the examination area in at least three phases is collectively measured by speckle-shearing interferometry.

10. The defect detection method according to claim 2 , wherein the displacement in the back-and-forth direction of each point within the examination area in at least three phases is collectively measured by speckle-shearing interferometry.

11. The defect detection method according to claim 3 , wherein the displacement in the back-and-forth direction of each point within the examination area in at least three phases is collectively measured by speckle-shearing interferometry.

12. The defect detection method according to claim 4 , wherein the displacement in the back-and-forth direction of each point within the examination area in at least three phases is collectively measured by speckle-shearing interferometry.

13. The defect detection method according to claim 5 , wherein the displacement in the back-and-forth direction of each point within the examination area in at least three phases is collectively measured by speckle-shearing interferometry.

14. The defect detection method according to claim 6 , wherein the displacement in the back-and-forth direction of each point within the examination area in at least three phases is collectively measured by speckle-shearing interferometry.

15. The defect detection method according to claim 7 , wherein the displacement in the back-and-forth direction of each point within the examination area in at least three phases is collectively measured by speckle-shearing interferometry.

16. The defect detection method according to claim 8 , wherein the displacement in the back-and-forth direction of each point within the examination area in at least three phases is collectively measured by speckle-shearing interferometry.

17. A defect detection device, comprising:
a) a first elastic wave inducer for inducing a first elastic wave in an object to be examined;
b) an illuminator for performing stroboscopic illumination on an examination area on a surface of the object to be examined;
c) a displacement measurement section for collectively measuring a displacement in a back-and-forth direction of each point within the examination area in at least three mutually different phases of the first elastic wave;
d) a second elastic wave injector, for injecting a second elastic wave into the inside of the object to be examined;
e) a response wave detector for detecting a response wave of the second elastic wave; and
f) a depth direction information acquirer for determining a location and/or size in a depth direction of the defect, based on the response wave.

Assignees

• Shimadzu Corp

Inventors

• Hatahori Takahide
• Nagata Yuya
• Takubo Kenji

Classifications

• G01N29/00

  Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object (G01N3/00 - G01N27/00 take precedence) · CPC title

• G01N29/44

  Processing the detected response signal {, e.g. electronic circuits specially adapted therefor (digital signal processing per se G06F17/00)} · CPC title

• G01N29/48

  by amplitude comparison · CPC title

• G01B9/02098

  Shearing interferometers · CPC title

• G01B9/02095 Primary

  detecting deformation from original shape · CPC title