National Institute of Advanced Industrial Science and Technology

Ishikawajima Inspection & Instrumentation Co., Ltd

Hiroshi Tsuda

Shien Ri

Takahiro Arakawa

Qinghua Wang

Jung-Ryul Lee

Tomio Nakajima

In a conventional moir&#xe9; method, achieving both measurement accuracy and dynamic measurement and balancing field of view and measurement accuracy have been difficult. The present invention makes it possible to handle conventional moir&#xe9; fringes as a grating for generating phase-shifted second-order moir&#xe9; fringes, use a spatial phase shift method algorithm to accurately analyze the phases of the second-order moir&#xe9; fringes before and after deformation, and determine shape from the phase differences between gratings projected onto the surface of an object of measurement and a reference surface and determine deformation and strain from the phase differences between the second-order moir&#xe9; fringes, before and after deformation, of a repeating pattern on the object surface or a produced grating. As a result, it is possible to measure the three-dimensional shape and deformation distribution of an object accurately and with a wide field of view or dynamically and with a high degree of accuracy.

Three-dimensional shape, displacement, and strain measurement device and method using periodic pattern, and program therefor

A vibration detection apparatus for, for example, ultrasound/AE, with Fiber Bragg Grating (FBG), is used for elastic wave detection generated by a material impact and ultrasonic defect detection. Disadvantageously, the apparatus cannot detect ultrasound and has degraded performance at variable temperatures and strains. In response, a highly sensitive, small and light vibration detection apparatus is provided. FBG reflection light is lased by using a fiber laser. The intensity of the lased reflection light from the FBG is converted into an electrical signal. Thus, the ultrasound vibration or the like is detected. A vibration detection system includes an optical amplifier, an optical circulator, and an optical coupler. An FBGand an entry/exit port of the optical circulator are connected by an optical fiber. The optical coupler and the optical amplifier are inserted between an entry port and an exit port of the optical circulator. The entry port and the exit port are connected by an optical fiber.

FBG vibration detection system, apparatus and vibration detection method using the system

There is provided a system always capable of detecting AE/ultrasound received by an FBG, even when the FBG receives a change in temperature or strain and the Bragg wavelength is fluctuated. In the AE/ultrasound detection system, the reflected light from the FBG is caused to enter a Fabry-Perot filter having an FSR equal to or greater than the reflection wavelength band of the FBG. A change in the intensity of the transmitted light corresponds to the AE/ultrasound received by the FBG. Alternatively, the reflected light from FBG is caused to enter two Fabry-Perot filters having an FSR equal to or greater than the reflection wavelength band of the FBG and having the filter-transmittance peak wavelengths different from each other by FSR/4. The intensity of the transmitted light from each of the two Fabry-Perot filters is converted into a voltage signal, and the individual signals are subjected to addition and subtraction processes. Thus, a signal having a large amplitude corresponding to the AE/ultrasound received by the FBG can be obtained.

AE/ultrasound detection system, and material monitoring apparatus and nondestructive inspection apparatus equipped the system

To provide an optical fiber strain sensor device and a strain detection method, for measuring precisely AE and for detecting effectively a rapid strain change due to a shock load, an optical fiber strain sensor device includes an FBG sensor mounted on an object to be measured, a broadband light source for directing a broadband wavelength light ray to the FBG sensor, and an FBG filter that reflects or transmits a light ray reflected from the FBG sensor, and, using the FBG filter, the optical fiber strain sensor device processes and detects a change in the center wavelength of the light ray that has been incident from the broadband light source and then has been reflected from the FBG sensor.

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Tsukuba, Japan

Hiroshi Tsuda