• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 하계학술발표회
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• pp.78-79
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• 2005

• 한국정밀공학회지
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• 제24권4호
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• pp.131-137
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• 2007

Electronic Speckle Pattern Interferometry(ESPI) is a common method for measuring out-of-plane deformation and in-plane deformation and applied for vibration analysis and strain/stress analysis. However, ESPI is sensitive to environmental disturbance, which provide the limitation of industrial application. On the other hand, Shearography based on shearing interferometer which is insensitive to vibration disturbance can directly measure the first derivative of out-of-plane deformation. In this paper a technique that extract out-of-plane deformation from results of shearography by numerical processing is proposed and measurement results of ESPI and Shearoraphy are compared quantitatively.

• 한국생산제조학회지
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• 제8권4호
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• pp.106-111
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• 1999

This study discusses a non-contact optical technique electronic, electronic speckle pattern interferometry(ESPI) that is well suited for in-plane and out-of-plane deformation measurement Used as specimen which has the boundary condition of two clamped parallel edges composite material AS4/PEEK[30/-30/90]s was analyzed by ESPI to determined the characteristics of tensile and vibration. These are quantitativly compared with the result of FEM analysis. Finally the results of this study are briefly summarized as follows : (1) In the in-plane strain analysis by comparison of theoretical results with experimental results qualitatively we confirmed that measurement errors are within 3 % in case of accuracy (2) From comparison of experimental vibration modes with numerical vibration mode shapes by the FEM analysis quantitatively we confirmed that vibration mode measurement by the ESPI has high accuacy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1803-1807
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• 2005

The pipe which it uses from the nuclear power plant or factory by a long period use and a corrosive action the inside defect occurs on the inside. abstract here. The ESPI method is in order to investigate the laser light in the measurement object it will be able to measure the wide territory whole in once, does not receive an effect in direction of defect not to be, has the strong point it will be able to measure a change of place arrowhead real-time defect. It measured a inside defect of pressure vessel by using Out of plane ESPI and In plane of ESPI. It compared a each method result.

• International Journal of Precision Engineering and Manufacturing
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• 제4권5호
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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.

• 비파괴검사학회지
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• 제32권2호
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• pp.177-184
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• 2012

ESPI는 비접촉 비파괴 방식으로 측정 대상체의 진동이나 변형에 따른 3차원 형상 정보의 취득에 효과적으로 사용되어 왔다. 측정 대상체와 계측 환경에 따라 면내, 면외, 전단간섭 등으로 구분할 수 있으며, 간섭계를 구성하는 광소자의 형태에 따라 벌크형과 광섬유형으로 나뉜다. 광섬유형 시스템은 크기가 작고 휴대하기 편하여 시스템 구성 및 정렬이 매우 용이하다. 본 논문에서는 광섬유 면외 ESPI를 이용한 광학계를 구성하였고, PZT를 이용하여 위상 변조를 ${\pi}/2$만큼 주기적으로 가하여 CCD 카메라에서 이미지를 획득하였다. 획득한 스페클 패턴 이미지는 후처리 과정을 통해 측정 대상체의 3차원 위상 정보를 얻게 된다. 내부 결함이 존재하는 압력용기에 질소 가스를 주입하여 변화되는 phase map을 관찰하였고, 또한 phase map의 후처리를 통하여 압력에 따른 대상체의 변화를 3차원으로 확인하였다.

• 한국광학회지
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• 제5권3호
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• pp.379-385
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• 1994

ESPI에서 물체를 비추는 입사광의 각도 및 거리에 따른 sensitivity vector를 구하고 입사광이 평행광일 때와 발산광일 때 두광원의 파면차이에 의한 변위의 민감도 차이를 비교하였다. In-plane 및 out-of-plane 면위에 민감한 ESPI 광학계 구성에 대해서 각각 분석하였다. 이 결과로부터 ESIP에서 입사광을 광학계의 구성이 용이한 발산광으로 하고 변위량의 계산에서는 물체 전면에서 sensitivity vector가 일정하다고 근사하는 것이 큰 오차가 없이 유용함을 알 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.226-230
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• 2001

Electronic Speckle Pattern Interferometry (ESPI) has been recently developed and widely used because it has advantage to be able to measure surface deformations of engineering components and materials in industrial areas with non-contact. The spekle patterns to be formed with interference phenomena of scattering phenomena measure the out-of-plane deformations, together with the use of digital image equipment to process the informations included in the speckle patterns and the display 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. Also, out-0of-plane displacements of a spot welded canti-levered plate were 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.

• 비파괴검사학회지
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• 제28권1호
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• pp.33-39
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• 2008

이중기능 간섭계는 ESPI와 전단간섭계의 모든 기능이 하나의 간섭계로 구성되어 있다. ESPI는 대상물의 변형을 측정하고 전단간섭계는 대상물의 변형의 기울기를 측정한다. 제안된 전단간섭법은 전단간섭계의 결과를 평행이동시킨 화소수로 나누고, 적분하면 원래의 변형과 거의 같은 결과를 얻을 수 있는데 이를 ESPI의 결과와 비교하였다. 본 연구에서는 고무판과 알루미늄 시험편을 이용하여 이중기능간섭계로 동시에 두 기법의 면외변형 결과를 측정하여 비교하였다. 이중기능간섭계는 동일한 한번의 변형에 두 가지의 결과를 동시 측정함으로써 두 기법의 정확한 비교가 가능하였다. 본 연구에서는 제안된 전단간섭법과 ESPI의 결과를 이중기능 간섭계를 이용하여 정량계측하여 만족한 결과를 도출하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1807-1812
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• 2007

A bulge testing system was developed to measure mechanical properties of thin film materials. A bulge pressure test system for pressurizing the bulge window of the film and a micro out-of-plane ESPI(Electronic Speckle Pattern Interferometric) system for measuring deflection of the film were included in the testing system developed. For the out-of-plane ESPI system, whole field speckle fringe pattern, corresponding to the out-of-plane deflection of the bulged film, was 3-dimensionally visualized using 4-bucket phase shifting algorithm and least square phase unwrapping algorithm. The bulge pressure for loading and unloading was controlled at a constant rate. From the pressure-deflection curve measured by this testing system, ain-plane stress-strain curve could be determined. In this study, elastic modulus of an electrolytic copper film 18 ${\mu}m$ was determined. The modulus was calculated from determining the plain-strain biaxial elastic modulus at the respective unloading slopes of the stress-strain curve and for the Poisson's ratio of 0.34.