• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.1
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• pp.92-99
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• 1997

Nowadays, Electronic Speckle Pattern Interferometry is a well-established measuring technique with a wide range of industrial applications, particularly in the fields of deformation measurement and vibration analysis. Comparing with holographic interferometry, it has some attractive features, which are rapid recording and reconstruction, satisfiable automation etc. The Time-Average ESPI is used to provide vibration mode shape of an object whose vibration amplitude is given as a fringe pattern. Its merit is rapid and simple measurement for vibrating object. However, it is not possible to determine the direction of motions of a point on the object at any given time, because it does not give any information about the phase of vibration. But, Stroboscopic ESPI can measure the amplitude and phase of vibrating surface. In this paper, loudspeakers were tested by these two methods. As a result, we can assume that these techniques will be applied directly in the loudspeaker industry.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.356-361
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• 1996

Nowadays, Electronic Speckle Pattern Interferometry is a well established measuring technique with a wide range of industrial applications, particularly in the fields of deformation measurement and vibration analysis. Comparing with holographic inteferometry, it has some attractive features, which are rapid recording and reconstruction, satisfiable automation etc. Time-average ESPI was used to provide vibration mode shape of an object whose vibration amplitude is given as a fringe pattern. However, it is not possible to determine the direction of motions of a point on the object at any given time, because time-average method does not give any information about the phase of vibration. A better technique is stroboscopic method which can measure the amplitude and phase of vibrating surface. In this paper, loudspeakers were tested by these two methods and the mode shape and amplitude of vibration were visualized. As measured results, we can assume that these techniques will be applied directly in the loudspeaker industry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.349-353
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• 2005

This paper describes the variations of resonance frequencies and vibration mode shapes of laser welded cold rolled carbon steel plate(SCP1) induced by thermal loading during laser welding processing. The characteristics of those are analyzed with stroboscopic ESPI. Electronic speckle pattern interferometry (ESPI) that the electronic processes were added to SPI is one of the very powerful method in the experimental vibration analysis field. Stroboscopic ESPI to make it reliable are compared with theory and experimental method: Finite Element Method(FEM) and Scanning Laser Doppler Vibrometer(SLDV). The results of stroboscopic ESPI are well agreed with SLDV and also the comparison with theory give good agrement within $5\%$.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.20-21
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• 2003

Electronic speckle pattern interferometry has many applications in science and engineering. Among these, vibration measurement is the area where ESPI has many advantages over other techniques. We developed a stroboscopic ESPI system to measure the harmonic vibration of a piece of copper tape attached to a circular hole structure. Figure 1 shows the schematic diagram of the stroboscopic ESPI system. (omitted)

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.97-104
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• 1999

Brake squeal noise has been a problem since the early days of motoring . It is important to obtain vibration mode shape for reduction of brake noise . Stroboscopic Electronic Speckle Pattern Interferometry is a very powerful measuring method for study of vibrating objects in static state compared with conventional methods because this method can give both resonance frequency and quantitative visualization of vibration mode shape at the same time. In this paper, we performed qualitative visualization and quantitative analysis of vibration mode shpae of disk brake by using stroboscopic ESPI and phase shifting method. The stroboscopic wavefronts are obtained by chopping continuous wave laser beam using acousto-optic modulator .Experiments were performed at the same constraint conditions as disk brake of the practical vehicle as far as possible. The experimental results of this paper show quantitative measurement of vibration mode shape and quantiative visualization of vibration amplitude of disk brake with 3D plotting.