• Title/Summary/Keyword: speckle interferometry

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Analysis of Vibration Characteristics by Using Electro-Optic Holography Method (전자광학 Holography법을 이용한 진동 특성 해석)

  • 김경석;차용훈;김형택;정현철;양승필;김정호
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.4
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    • pp.98-104
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    • 1998
  • Recently. a new technique called Electronic Speckle Pattern Interferometry(ESPI) has been developed to overcome the drawbacks of existing holography. This technique enable real-time interference fringes to be displayed directly on TV monitor without recourse to any form of photographic processing. This research was carried out for the purpose of applying the vibration analysis method employing Electronic Speckle Pattern Interference technique to the vibration analysis of uniform rectangular cantilever plate. The natural vibration frequencies found by ESPI were in fair agreement with theoretical eigen frequencies acquired using theoretical formula G. B. Warburton proposed.

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Development of electronic shearography for vibration analysis (진동해석을 위한 전자전단간섭계의 개발)

  • Kang, Young-June;Kwon, Yong-Ki
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.12
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    • pp.2047-2054
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    • 1997
  • This paper describes a measuring method of vibration mode shapes by the Electronic Shearography. This method called the speckle interferometer has many merits in practical use, such as low sensitivity to environmental noise, low limit of coherent-length and simple optical configuration. In this study, we developed Michelson-type shearing interferometer provided with a phase stepping mirror and with a bias modulation mirror to quantify the vibration gradient fields. Results of application to a simple cantilever plate show that the vibration amplitude fields obtained are in good agreement with those of the electronic speckle pattern interferometry (ESPI).

Holospeckle interferometry for measureen of 3-D displacement (3차원 변위측정을 위한 홀로스펙클 간섭법)

  • 박승옥
    • Proceedings of the Optical Society of Korea Conference
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    • 1990.02a
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    • pp.131-135
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    • 1990
  • The combined technique of holographic interferometry and speckle photography, so called holospeckle interferometry, has been attention for the measurement of 3-D displacements. This new technique enables the researcher to obtain information of in plane and out-of plane displacements from one photographic plate. There is room for further development of special optical arrangement in order to apply holospeckle interferometry in specific field. In this study, the enlarged fringe pattern was obtained by specifical optical arrangement.

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Application of ESPI to Measurement of Out-of-plane Displacement in a Spot Welded Canti-levered Plate

  • Baek, Tae-Hyun;Kim, Myung-Soo;Na, Eui-Gyun;Koh, Seung-Kee
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.5
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    • pp.41-46
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    • 2003
  • Electronic Speckle Pattern Interferometry (ESPI) has been recently developed and widely used because it has the advantage of being able to measure surface deformations of engineering components and materials in industrial areas without contact. The speckle patterns formed with interference and scattering phenomena can measure not only the out-of-plane but also the in-plane deformations. Digital image equipment processes the information included in the speckle patterns and displays the consequent interferogram on a computer monitor. In this study, the experimental results of a canti-levered plate using ESPI were compared with those obtained from the simple beam theory. The ESPI results of the canti-levered plate, analyzed by 4-step phase shifting method, are close to the theoretical expectation. Similarly, out-of-plane displacements of a spot welded canti-levered plate were also measured by ESPI with 4-step phase shifting technique. The phase map of the spot welded canti-levered plate is quite different from that of the canti-levered plate without spot welding.

Improvement of Contour Fringes by using Addition of Incremental Images (화상 증분 축적법을 이용한 등고선 간섭무늬의 개선)

  • Kang, Young-June;Kim, Gye-Sung;Ryu, Weon-Jae;Kwon, Yong-Ki
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.12
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    • pp.190-197
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    • 1999
  • Electronic speckle contouring(ESC) is the optical method for measuring shape by using fringe-projection techniques in electronic speckle pattern interferometry. It has the advantage of being non-contacting and can also give a field view of the surface under investigation. Fringes in ESC represent the difference in depth along the view direction between the master wavefront and the test component. The contour maps of three-dimensional diffuse objects are obtained by small shifts of optical fiber carrying the dual-object-beams and 4-frame phase shift. We proposed the contouring method by shifting the collimated illumination beams through optical fiber in order to obtain the contour fringe patterns. And also, we performed addition of incremental addition of images and experiments based on it. we obtained both quantitative increment without decorrelation effect and qualitative improvement by reducing the noise of contour fringes.

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Improvement of Contour Fringes by using Addition of Incremental Images

  • Kang, Young-June;Ryu, Weon-Jae;Park, Sang-Kyu
    • International Journal of Precision Engineering and Manufacturing
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    • v.3 no.3
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    • pp.37-43
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    • 2002
  • Electronic speckle contouring(ESC) based on electronic speckle pattern interferometry is the optical method for measuring object shape by using fringe-projection techniques. This method has the advantages of being non-contact, non-destructive and a whole-field measurement of the surface under investigation. Fringes in ESC represent the difference in depth along the view direction between the master wavefront and the test component. The contour maps of three-dimensional diffuse objects can be obtained by small shifts of optical fiber carrying the dual-object-beams and 4-frame phase shifting. In this study we proposed the contouring method by shifting the collimated illumination beams through optical fiber in order to obtain the contour fringe patterns. And also, we performed the addition of incremental images through the geometrical analysis to obtain the contour fringe interval when we performed the incremental addition of images and experiments based on this method. We obtained both quantitative increment without decorrelation effect and qualitative improvement by reducing the noise of contour fringes.

Measurement of 3-D Deformation by Using Holospeckle Interferometry (홀로스펙클 간섭법을 이용한 3차원 변형측정 연구)

  • 박승옥;권영하;유성규
    • Korean Journal of Optics and Photonics
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    • v.1 no.1
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    • pp.12-15
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    • 1990
  • Holospeckle interferometry, the combined technique of holographic interferometry and speckle photography, was applied to the measurement of 3-D contact deformation created by an indentor. This new tech$.$ nique makes possible to measure both in-plane and out-of-plane displacements from one photographic plate. In this study, the optical system based on image holography was set up. In order to enhance the size and the contrast of the speckle, a proper magnification and a low reference beam ratio was used as compared with the conventional holographic interferometry technique. This system shows the magnified and clear holographic interference fringe as well as Young's fringe patterns.tterns.

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