• Journal of Welding and Joining
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• 제17권1호
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• pp.71-76
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• 1999

The real-time holographic interferometer with digital high-speed camera is applied to the experimental study of laser induced plasma/plume in pulsed Nd:YAG laser welding. A pulsed Nd:YAG laser with 1.2 kW average power is applied to generate laser induced plume. The recording speed of the high-speed camera is 3,000 f/s. The high speed photographs of weld plume without another visualization method, are compared with the visualization photographs with holographic interferometer. The radiation intensity from the laser induced plume is recorded by the high speed photographs, which fluctuated during laser radiation and disappeared after laser end. The density distribution of the plume is recorded by the holographic visualization method. The experimental results show the process of generation of the laser induced plasma/plume, and give the feasibility of quantitative measurement of laser induced plume in laser welding.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.922-925
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• 2005

This article describes a FM modulation algorithm to increase the measurement speed by increasing the beat frequency of the laser without acousto-optic modulator(AOM) in the heterodyne laser interferometer. The proposed algorithm can increase the beat frequency of the heterodyne laser which limit the measurement speed by adjusting a carrier frequency through electronic circuit, while AOM is used to shift the frequency of the heterodyne laser in conventional method. Electronic circuit is constructed to modulate the signals from a laser interferometer and a waveform generator. The brier analysis, the measurement scheme of the system, and the experimental results using a Zeeman-stabilized He-Ne laser are presented. They demonstrate that the proposed algorithm is proven to enhance the measurement speed limit by increasing the beat frequency of the heterodyne laser.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.371-374
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• 1995

The real-time holographic interferometer with a digital high-speed camera is applied to the visualization of transient temperature field. Collimated and diffused laser beams are used to the object beam according to the shape and transmittance of the phase object. Also, ESPI(Electronic Speckle Speckle Pattern Interferometer) technique is used to the visualization and quantitatie measurement of slow-varying temperature field. The experimental results obtained form these two techniques are discussed.

• 한국기계가공학회지
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• 제6권4호
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• pp.22-27
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• 2007

This study aims to find the optimal cutting conditions, when ellipse mirrors consisted Aluminum alloy were made it the Millimeter-Wave Interferometer System mirror with several tools on the High-Speed Machine. Machining technique for precision machining characteristics of ellipse mirrors consisted Al6061 matter by Ball endmill is reported in this paper., Results of machining on the High-Speed Machine(using NCD(Natural Crystalline diamond), WC and coated TiAlN ${\phi}6mm$ ball endmill tool) had measurement of surface roughness and form accuracy with cutting conditions(the Feed rate, the Depth of cut and the Cutting speed). the Millimeter-Wave Interferometer System ellipse mirror had been machined foundational precision machining characteristics of aluminum.

• 한국정밀공학회지
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• 제22권11호
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• pp.91-98
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• 2005

This study has been focused on the development of a high speed feeding type three-dimensional bending machine. It is designed for manufacture of copper pipe for heat exchangers. For the purpose of design of the machine, analysis of bending process, structural analysis and reliability evaluation of the machine by a laser interferometer are carried out. The analysis is carried out by FEM simulation using commercial softwares, DEFORM, MARC and CATIA V5. In addition, the machine has attained high accuracy and repeatability. In order to improve the accuracy of this machine, the maximum speed, positioning accuracy and repeatability of feed are measured by the laser interferometer. The final results of analysis are applied to the design of a high speed feeding type three-dimensional bending machine and the machine is successfully developed.

• 한국정밀공학회지
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• 제30권7호
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• pp.702-708
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• 2013

The white-light scanning interferometer (WSI) is an effective optical measurement system for high-precision industries (e.g., flat-panel display and electronics packaging manufacturers) and semiconductor manufacturing industries. Its major disadvantages include a slow image-capturing speed for interferogram acquisition and a high computational cost for peak-detection on the acquired interferogram. Here, a WSI system is proposed for the semiconductor inspection process. The new imaging acquisition technique uses an 'on-the-fly' imaging system. During the vertical scanning motion of the WSI, interference fringe images are sequentially acquired at a series of pre-defined lens positions, without conventional stepwise motions. To reduce the calculation time, a parallel computing method is used to link multiple personal computers (PCs). Experiments were performed to evaluate the proposed high-speed WSI system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.69-70
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• 2009

• Journal of the Optical Society of Korea
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• 제9권1호
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• pp.22-25
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• 2005

The differential heterodyne interferometer (DHI) is suitable for precise measurement of step height and line width, since its differential configuration can significantly reduce disturbances from the environment [1,2]. Like most phase measuring interferometers, however, the DHI is limited, in that it can obtain only the phase from 0 to 2π, because of the sinusoidal nature of the optical interference involved. Thus, the measurable step height is limited to one quarter of the wavelength of the light source. This study describes a confocal differential heterodyne interferometer (CDHI) for measuring step heights of several micrometers, with a high resolution and line width with high repeatability. The CDHI has a simple structure and rapid measurement speed.

• 한국공작기계학회논문집
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• 제10권4호
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• pp.97-103
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• 2001

The study on the high-speed machine tool is very important for the improvement of productivity since it can shortens cutting and non-cutting time. Especially, high speed of feed drive system is the major research field. In the industries of the advanced countries, the feed drive systems at the speed of 60 m/min have been already developed based on the high lead ball screws. In this study, a high speed feed drive system at the speed of 60 m/ min has been developed, and its movements characteris-tics are investigated. As the movement characteristics, positioning accuracy, angular accuracy, straightness and micro step-response are measured. Thermal characteristics of the system is also discussed. For measuring the movement characteris-tics, a laser interferometer, a memory-based Hi-coder and a cooling device are used. The experimental results confirm that the movement characteristics and the thermal behavior of the system are satisfactory in the aspect of accuracy and stability.

• 대한전자공학회논문지SD
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• 제43권11호
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• pp.14-18
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• 2006

광간섭계는 물체의 기하학적 구조 및 의료 계측등 다양한 분야의 광계측에서 매우 일반적으로 사용된다. 이러한 광간섭계에서 광지연단은 측정대상의 기준을 위해 사용되고. 광간섭계의 계측속도는 광지연단에 의해 제한된다. 본 논문에서는 고속 광지연단을 위해 기존의 기계적 방식을 배제하고, 광학적 방식의 광 간섭계를 구성하였다. 고속 광간섭계의 구성은 1304nm의 10GHz광원을 이용하였으며, 광지연단으로 광위상변조기와 광섬유를 이용하여 안정적이고 고속의 광 간섭계를 구성하였다. 구성된 광간섭계는 광위상변조기의 변조전압, 변조주파수에 의해 광지연시간을 가변할 수 있으며, 10MHz 반복율에 대해 11ps의 광지연시간을 얻을 수 있었다.