Laser-based maintenance apparatus for inspecting flaws based on a generated surface wave

• US 8,248,595 B2
• Filed: 09/19/2011
• Issued: 08/21/2012
• Est. Priority Date: 07/07/2005
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ochiai, Makoto, Miura, Takahiro, Kuroda, Hidehiko, Osakata, Fukashi, Yamamoto, Satoshi, Tsuchihashi, Kentaro, Yoshida, Masahiro, Tsuyuki, Akira
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): LaPage, Michael P
• Application Number:
  US13/236,322
• Publication Number:
  US 20120048021A1
• Time in Patent Office: 337 Days
• Field of Search: 356/237.2, 356/240.1, 356/241.1, 3562371-2416, 356/502
• US Class Current: 356/237.2
• CPC Class Codes: F22B 37/003 Maintenance, repairing or inspecting equipment positioned in or via the headers
• CPC Class Codes: G01B 11/161 by interferometric means
• CPC Class Codes: G01B 17/02 for measuring thickness
• CPC Class Codes: G01B 2290/25 Fabry-Perot in interferometer, e.g. etalon, cavity
• CPC Class Codes: G01N 2291/0258 Structural degradation, e.g. fatigue of composites, ageing of oils
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 2291/0421 Longitudinal waves
• CPC Class Codes: G01N 2291/2636 cylindrical from inside
• CPC Class Codes: G01N 29/043 in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/0645 Display representation or displayed parameters, e.g. A-, B- or C-Scan
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves
• 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: G21C 17/003 Remote inspection of vessels, e.g. pressure vessels
• CPC Class Codes: G21C 17/017 Inspection or maintenance of pipe-lines or tubes in nuclear installations
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

A surface inspecting method including irradiating a laser light to a test object to generate an ultrasonic wave, irradiating a second laser light at a position apart by a known distance from a position where the laser light is irradiated and receiving a reflection light thereof, and correcting a generation surface wave of a received ultrasonic wave by using an ultrasonic wave other than the generation surface wave to thereby detect a flaw of the test object. A characterization of the generation surface wave is divided or integrated by the same characterization of the ultrasonic wave other than the generation surface wave included in an output signal to obtain a performance index value and obtain a depth of the flaw by applying the performance index value to a calibration curve in which a corresponding relation between the performance index value and the depth of the flaw is obtained preliminarily.

Claims

1. A surface inspecting method comprising the steps of:

irradiating a laser light to a test object to be inspected so as to generate an ultrasonic wave;

irradiating a second laser light at a position apart by a known distance from a position where the laser light is irradiated and receiving a reflection light thereof; and

correcting a generation surface wave of a received ultrasonic wave by using an ultrasonic wave other than the generation surface wave to thereby detect a flaw of the test object,

wherein a characterization of the generation surface wave is divided or integrated by the same characterization of the ultrasonic wave other than the generation surface wave included in an output signal to obtain a performance index value and obtain a depth of the flaw by applying the performance index value to a calibration curve in which a corresponding relation between the performance index value and the depth of the flaw is obtained preliminarily.

2. The surface inspecting method according to claim 1, wherein the ultrasonic wave other than the surface wave is at least one of a longitudinal wave and a volume wave which are propagated over a surface layer of the test object to be inspected.

3. The surface inspecting method according to claim 1, wherein both the characterizations of the surface wave and the ultrasonic wave other than the surface wave are the root mean-square values of amplitude.

4. The surface inspecting method according to claim 1, wherein both the characterizations of the surface wave and the ultrasonic wave other than the surface wave are integrated values of power spectra.

5. The surface inspecting method according to claim 4, wherein an integration range of the power spectra is arbitrarily selected.

6. A surface inspecting device comprising:

an ultrasonic generating unit for irradiating a laser light to a test object to be inspected so as to generate an ultrasonic wave;

an ultrasonic receiving unit for irradiating a second laser light to a position apart by a known distance from a position where the laser light from the ultrasonic generating device is irradiated and receiving an ultrasonic wave by receiving a reflection light thereof; and

a processing unit that inputs and records the output signal from the ultrasonic receiving device so as to detect a flaw of the test object,

wherein the processing unit corrects a generation surface wave of the output signal with an ultrasonic wave other than a surface wave, and

wherein the processing unit divides or integrates a characterization of the generation surface wave by the same characterization of the ultrasonic wave other than the surface wave included in an output signal to obtain a performance index value and obtain a depth of the flaw by applying the performance index value to a calibration curve in which a corresponding relation between the performance index value and the depth of the flaw is obtained preliminarily.