Optical inspection system, optical inspection method, and aircraft structure

Patent metadata

Field	Value
Publication number	US-11105657-B2
Application number	US-201916373965-A
Country	US
Kind code	B2
Filing date	Apr 3, 2019
Priority date	May 30, 2018
Publication date	Aug 31, 2021
Grant date	Aug 31, 2021

Abstract

An optical inspection system includes an optical fiber sensor, an optical filter, a signal processor, and a corrector. The optical fiber sensor outputs a first optical signal having a temporal change in a wavelength corresponding to a temporal change in an amplitude of a vibration propagating in an inspection target object or a temporal change in a displacement of the inspection target object. The optical filter converts the first optical signal into a second optical signal having a temporal change in an intensity. The signal processor acquires inspection information on the inspection target object on the basis of the second optical signal. The corrector corrects a correspondence relationship between the temporal change in the wavelength and the temporal change in the intensity by changing a wavelength characteristic of the optical filter. The correspondence relationship is directed to converting the first optical signal into the second optical signal.

First claim

The invention claimed is:

1. An optical inspection system comprising:
an optical fiber sensor configured to detect a vibration propagating in an inspection target object or a displacement of the inspection target object and to output a first optical signal having a temporal change in a wavelength, the temporal change in the wavelength corresponding to a temporal change in an amplitude of the vibration or a temporal change in the displacement;
an optical filter configured to convert the first optical signal into a second optical signal having a temporal change in an intensity and to output the second optical signal, the temporal change in the intensity corresponding to the temporal change in the wavelength;
a signal processor configured to acquire inspection information on the inspection target object on a basis of the second optical signal;
a corrector configured to correct a correspondence relationship between the temporal change in the wavelength of the first optical signal and the temporal change in the intensity of the second optical signal by changing a wavelength characteristic of the optical filter, the correspondence relationship being directed to converting the first optical signal into the second optical signal; and
a storage device configured to store information indicating a relationship between a temperature of the inspection target object and an amount of change in the wavelength characteristic of the optical filter, and
wherein the corrector changes the wavelength characteristic of the optical filter by an amount of change corresponding to the temperature of the inspection target object.

2. The optical inspection system according to claim 1 , wherein the optical filter comprises an arrayed waveguide grating, a fiber Bragg grating, or a phase-shifted fiber Bragg grating.

3. The optical inspection system according to claim 1 , wherein the signal processor acquires, as the inspection information, information as to whether a defect is present in the inspection target object, or information indicating a degree of the defect present in the inspection target object, or both.

4. The optical inspection system according to claim 1 , wherein
the optical filter includes an optical waveguide, and
the corrector changes the wavelength characteristic of the optical filter by adjusting a temperature of the optical waveguide.

5. An aircraft structure comprising the optical inspection system according to claim 1 .

6. An optical inspection method comprising acquiring inspection information on an inspection target object by the optical inspection system according to claim 1 .

7. The optical inspection system according to claim 1
wherein the signal processor configured to acquire inspection information on the inspection target object on the basis of the second optical signal includes circuitry configured to acquire the inspection information on the inspection target object on the basis of the second optical signal, and
the corrector includes circuitry that is configured to correct the correspondence relationship between the temporal change in the wavelength of the first optical signal and the temporal change in the intensity of the second optical signal by changing the wavelength characteristic of the optical filter, the correspondence relationship being directed to converting the first optical signal into the second optical signal.

8. The optical inspection system according to claim 1 , wherein the optical filter comprises an arrayed waveguide grating.

9. An optical inspection system comprising:
an optical fiber sensor configured to detect a vibration propagating in an inspection target object or a displacement of the inspection target object and to output a first optical signal having a temporal change in a wavelength the temporal change in the wavelength corresponding to a temporal change in an amplitude of the vibration or a temporal change in the displacement;
an optical filter configured to convert the first optical signal into a second optical signal having a temporal change in an intensity and to output the second optical signal, the temporal change in the intensity corresponding to the temporal change in the wavelength;
a signal processor configured to acquire inspection information on the inspection target object on a basis of the second optical signal;
a corrector configured to correct a correspondence relationship between the temporal change in the wavelength of the first optical signal and the temporal change in the intensity of the second optical signal b changing a wavelength characteristic of the optical filter, the correspondence relationship being directed to converting the first optical signal into the second optical signal; and
a storage device configured to store information indicating a relationship between an amount of strain in the inspection target object and an amount of change in the wavelength characteristic of the optical filter, and
wherein the corrector changes the wavelength characteristic of the optical filter by an amount of change corresponding to the amount of strain in the inspection target object.

10. The optical inspection system according to claim 9 , wherein the signal processor acquires, as the inspection information, an amount of strain in the inspection target object.

11. The optical inspection system according to claim 9 , wherein
the optical filter includes an optical waveguide, and
the corrector changes the wavelength characteristic of the optical filter by causing the optical waveguide to expand or contract.

12. An aircraft structure comprising the optical inspection system according to claim 6 .

13. An optical inspection method, comprising acquiring inspection information on an inspection target object by the optical inspection system according to claim 6 .

14. The optical inspection system according to claim 9 , wherein
the signal processor, that is configured to acquire inspection information on the inspection target object on the basis of the second optical signal, includes circuitry configured to acquire the inspection information on the inspection target object on the basis of the second optical signal, and
the corrector includes circuitry that is configured to correct the correspondence relationship between the temporal change in the wavelength of the first optical signal and the temporal change in the intensity of the second optical signal by changing the wavelength characteristic of the optical filter, the correspondence relationship being directed to converting the first optical signal into the second optical signal, and
wherein the signal processor acquires, as the inspection information, information as to whether a defect is present in the inspection target object, or information indicating a degree of the defect present in the inspection target object, or both.

15. The optical inspection system according to claim 9 , wherein the optical filter comprises an arrayed waveguide grating.

16. An optical inspection system comprising:
an optical fiber sensor configured to detect a vibration propagating in an inspection target object or a displacement of the inspection target object and to output a first optical signal having a temporal change in a wavelength the temporal change in the wavelength corresponding to a temporal change in an amplitude of the vibration or a temporal change in the displacement;
an optical filter configured to convert the first optical signal into a second optical signal having a temporal change in an intensity and to output the second optical signal, the temporal change in the intensity corresponding to th

Assignees

• Subaru Corp

Inventors

• Soejima Hideki
• Ogisu Toshimichi

Classifications

• G02B6/12009

  comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides · CPC title

• G01B11/02

  for measuring length, width or thickness (G01B11/08 takes precedence) · CPC title

• G01M5/0066

  by exciting or detecting vibration or acceleration (vibration testing of structures G01M7/00) · CPC title

• G01H9/004

  using fibre optic sensors (light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125) · CPC title

• G01M11/083

  by using an optical fiber in contact with the device under test [DUT] · CPC title