• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.36-43
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• 2006

• 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).

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.4
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• pp.402-410
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• 2002

Recently the necessity of study on optical measuring method using laser to detect the pipeline's defect in nuclear facilities, chemical industries and power plants has been increased. Because laser light can be delivered to a remote area without any difficulties, the application of laser in many industries can solve several difficulties from the limitation of access in danger area and reduce the risks of workers. Therefore, we applied a new experimental technique to the measurement of internal defects in pressure vessels with the combination of shearography and image processing technique and detected the internal cracks of pressure vessels in the former paper. In this paper, we used the same optical system as in the former study and found the optimum shearing magnitude by comparing the real length of specimen with experimental results. A variety of conditions were applied to certify the validity of this method. Actually, several specimens which have different lengths and depths were used in this experiment under the three diverse pressure. Consequently, we have carried out this experiment to determine the limit of measurement ability with analyzing errors.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.4 s.193
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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.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.235-243
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• 2002

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.140-143
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• 2001

Digital shearography, a speckle pattern method is based on the superposition of two laterally sheared images. Therefore, object points which are positioned in some distance from each other are superposed in the image plane. This shearography, one of NDT methods without contact, is able to inspect defects in pipelines and pressure vessels that are used in nuclear power plants. This is can inspect whole fields and has a low sensitivity to environmental noise. Because optical setting is very simple, it has a little exhaustion of time, cost and man power. And also it can find a defect position through real time monitoring of a part. This paper, finds out the relationship among shearing quantity image quality and defect size with this method.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.59-66
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• 2013

The measuring of internal defects of objects using the shearography has many advantages. It is a non-contact and non-destructive method and It has a real time measurement speed and no constraints of object shape. Compared to ESPI(Electronic Speckle Pattern Interferometry), Shearography has a very low error rate by vibration and air turbulence. So shearography provides possibilities of industrial application. In this paper, Image processing algorithm that is measurement of out-of-plane deformation using the shearography is proposed by developed using the LabVIEW 2010 and measurement result of out-of-plane ESPI and Shearography are compared quantitatively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.195-198
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• 2001

Backside defect of plate structure may grow due to fatigue or overload to cause critical failure during operation, so it is important to detect this kind of defect in line. For this purpose, nondestructive, non-contact and highly sensitive method is required. ESPI and Shearography are considered as useful method to satisfy these requirements. In this paper, the possibility of application of ESPI and Shearography to detect the backside defect of steel plate and to quantify the defect size was tested. For the experiment, some steel plates with defect on the backside were prepared. Experimental results for these plates showed that location and size of defect could be detected correctly by both of ESPI and Shearography.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.1-8
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• 2003

Thermo-mechanical behavior of a ceramic ball grid array (CBGA) package assembly are characterized by high sensitive moire interferometry. Moir fringe patterns are recorded and analyzed at various temperatures in a temperature cycle. Thermal-history dependent analyses of global and local deformations are presented, and bending deformation (warpage) of the package and shear strain in the rightmost solder ball are discussed. A significant non-linear global behavior is documented due to stress relaxation at high temperature. Analysis of the solder interconnections reveals that inelastic deformation accumulates on only eutectic solder fillet region at high temperatures.