• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.156-164
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• 1998

Electronic Speckle Pattern Interferometry(ESPI) has been used to measure surface deformations of engineering components and materials in industrial areas. ESPI, a non-contact and non-destructive technique, is capable of providing full-field results with high spatial resolution and high speed. One of the important application using electronic speckle pattern interferometry is electronic speckle contouring of a diffused object for 3-D shape analysis and topography measurement. Generally the electronic speckle contouring is suitable for providing measurement range from millimeters to several centimeters. In this study, we introduce the contouring method by modified dual-beam speckle pattern interferometer and the shift of the two illumination beams through optical fiber in order to obtain the contour fringe patterns. We also describe formation process of depth contour fringes and grid contour fringes by shifting direction of the two illumination beams. Before the experiments, we performed the geometric analysis for dual-beam-shifted ESPI contouring, and then, the electronic speckle contouring experiment with various specimens. For quantitative analysis of the contour fringes, we used 4-frame phase shifting method with PZT Finally, good agreement between the geometric analysis and experimetal results is obtained.

• 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.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.2
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• pp.81-86
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• 2005

This paper proposes a non-destructive ESPI technique to quantitatively evaluate defects inside a semiconductor package. The inspection system consists of the ESPI system, a thermal loading system and an adiabatic chamber. The technique is high feasibility for non-destructive testing of a semiconductor and overcomes the weaknesses of previous techniques, such as time-consumption and difficult quantitative evaluation. Most defects are classified as delamination defects, resulting from the insufficient adhesive strength between layers and from non-homogeneous heat spread. Ninety percent of the tested samples had delamination defects which originated at the corner of the chip and nay be related to heat spread design.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.97-104
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• 2009

There is a many kinds with nondestructive testing such as RT and UT representatively. Referred before two testing methods there is a limit which is spatial such as nuclear pipe, small vessel, sealing up vessel. So a new technique needs to overcome the limit which is spatial. shearography will be able to overcome the limit which is spatial. This paper introducing shearography which was known as non-contact full-field testing method and It is an interferometric technique for measurement of surface deformation such as displacement or displacement gradient. Also, a research about internal defect of the flange welding zone was accomplished. About variation with method pressurized with the Gaseous Nitrogen. Phase map where is various were measured according to changing a sheared direction, size of crack and loaded pressure. Consequently, crack quantitatively to be detected qualitatively was measured by using shearography.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1382-1390
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• 1995

Electronic Speckle Pattern Interferometry (ESPI) with a CW laser, a video system and an image processor was utilized to measure the in-plane displacement. Unlike traditional strain gauges or Moire method. ESPI method measure the in-plane displacement on real time with out any surface preparation on surface attachment. The specimen has a crack of 10*0.1 mm in the middle of plate and strain gauge was also attached on that surface to compare with ESPI method. This study reveled the ESPI method to measure the displacement and distribution of strain in the specimen. It was shown in tensile tests that the measurement by ESPI method was comparable with strain gauge.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.136.1-136.1
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• 2005

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.1
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• pp.18-22
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• 2014

Residual stresses that occur during the welding process, are the main cause of failure and defects in welded structures. This paper, presents the use of an electronic processing laser speckle interferometer to measure the residual stress of a welded pipe for a nuclear power plant. A tensile testing machine was used to evaluate a welded pipe that failed in compression. The inform plane deformation and modulus of elasticity of the base metal and welds were measured using an interferometer. Varying the load on the welded pipe had a larger effect on the deformation of the base metal the other properties of the base metal and welds. The elastic moduli of the base metal and weld of the welded pipe were 202.46 and 212.14 GPa, respectively, the residual stress was measured to be 6.29 MPa.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.556-560
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• 2005

The measurement method by Laser Speckle Interferometry which uses the interference law which will grow precedes and with it explains a resolution measurement ability and together the change of place arrowhead and general measurement, at real-time measurement sensitivity it has application boat song from candle precise measurement field it is increasing. But, currently the domestic application technique to sleeps and optical science military merit by optical science interferometer and directness it composes purchases to the level which it applies the expensive commercial business equipment the outside and in spite of the technical ripple effect is deficient even in many strong point. The hazard which complements like this problem point form technical development it leads from the research which it sees and an application degree and to sleep as the measurement equipment which tries to develop the small-sized optical science interference sensor and an interpretation program it raises it does.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.85-90
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• 1996

In the word, there is varied types of vibration, and these affect the mechanical industry. In this paper is plates with two parallel sides fixed. Electronic speckle pattern interferometry (ESPI) is one of the optical nondestructive testing technique. By using the ESPI, vibration modes for excitation point, a/b(ratio of longuitudinal and lateral length), and kind of specimen are measured and compared qualitatively with theoritical analysis that Warburton proposed.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.772-776
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• 2004

The paper describes the quantitative determination of out-of-plane displacement from result of Shearogrpahy, which can measure the first-order partial derivative of out-of-plane displacement directly. However, the differential sensitivity of Shearography is related to the amount of shearing, which is manually adjustable in optical interferometer and affects the quantitative determination. The relationship between those is inspected by comparing ESPI with Shearography. From the result, the amount of shearing plays a modulation factor of out-of-plane displacement and small amount of shearing gives good agreement with out-of-plane displacement.