2002 Fiscal Year Final Research Report Summary
Development of a Laser Speckle Interferometer to Measure Two-dimensional In-plane Vibration in Real-time Based on Fourier Transform with Electronic Circuit
| Project/Area Number |
13555063
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Dynamics/Control
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
IWATSUKI Nobuyuki Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院・理工学研究科, 教授 (70193753)
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| Co-Investigator(Kenkyū-buntansha) |
SAITOH Masatake Suzuki Co. Ltd., Yokohama Technical Center, Head, 技術研究所, 研究員
GOTOH Hiroshi Sumsung Co. Ltd., Technical Center, Research Engineer, 総合技術院, 研究員
MORIKAWA Kouichi Tokyo Institute of Technology, Graduate School of Science and Engineering, Research Associate, 大学院・理工学研究科, 助手 (00282830)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Vibration Measurement / Laser Speckle Interferometer / Two-dimensional Displacement / Phase Detector / 2D Fourier Transform / Analogue Electronic Circuit / Image Sensor / Measuring Accuracy |
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| Research Abstract |
Aiming to develop a high-performance vibrometer which can measure multi-dimensional displacement with high accuracy in real-time, a new laser speckle interferometer based on the quad aperture method with a phase detector of interference image using two-dimensional Fourier transform was proposed and was theoretically and experimentally examined. Analogue electronic circuit for two-dimensional Fourier transform was then designed. The results obtained are summarized as follows.
(1)A prototype of a laser speckle interferometer with the quad aperture method was built. And by detecting a two-dimensional displacement of lattice type interference image with correlation method, a two-dimensional displacement of a target can be measured.
(2)Two-dimensional Fourier transform of the lattice type interference image was theoretically derived. It was then revealed that displacement of the target was in proportion to the phase spectrum at the spatial frequency twice as high as the fundamental spatial frequency of interference image and that the calculation cost could be remarkably reduced in compare with that of the correlation method.
(3)Experiments to measure the two-dimensional static displacement were carried out and then the factors to cause measuring error were discussed. It was revealed that the measuring error became smaller as the average visibility of the interference image was higher and as the phase variation in the image was smaller.
(4)By selecting laser irradiation point so that the average visibility of the interference image is high and that the phase variation in the image is small, and by applying the 25 points median filter to the image, the measuring error becomes reduced.
(5)An analogue electronic circuit which can calculate the phase of the fundamental frequency component of the interference image obtained with C-MOS image sensor according to two-dimensional Fourier Transform in real-time was designed.
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Research Products
(6 results)
