• Applied Microscopy
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• v.35 no.4
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• pp.64-73
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• 2005

In this paper we discussed in details how to determine the nature of dislocations in a crystal such as a Burgers vector, the line vector of dislocation and the associated slip plane, using LACBED and usual imaging techniques. These techniques basically involve the application of Cherns and Prestone s rules, the simulations of LACBED patterns with a certain form of the dynamical diffraction theory. The theoretical aspects including necessary approximations for calculations also were in details discussed. As a test specimen for experiments, the foils of a pure aluminum, containing many dislocations with appropriate density for LACBED experiments, were used..

• Applied Microscopy
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• v.33 no.3
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• pp.195-204
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• 2003

The Experimental calibration method has been investigated to correct d-spacing estimation and to identify phases in the electron diffraction data acquired by imaging plates. When the diffraction data from the imaging plate was corrected by the d-spacing calibration method with the radial intensity distribution plotting in this experiment, The accuracy of d-spacing estimation was significantly increased in errors of about 0.5%. The experimental calibration equation followed up the first order exponential decay function was derived from the trace of d-spacing deviation between the measured and the calculated values. It was applied to the analysis of d-spacing and the phase identification of the transitional phases formed from [001] gibbsite specimen by electron beam irradiation effect. In this case more accurate phase identification and d-spacing evaluation is possible for the transitional phases whose diffraction patterns are complicatedly superimposed. It is concluded that ${\chi}$-alumina, ${\gamma}$-alumina and ${\sigma}$-alumina are clearly identified as the major transitional phases formed from gibbsite by electron beam irradiation for 120 min.

• Advanced Industrial SCIence
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• v.2 no.4
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• pp.28-35
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• 2023

In this paper, a diffractive optical element was designed to create lighting patterns that satisfy the requirements of adaptive headlight systems for normal road mode, highway mode, and wet road mode, and this was rendered into a GDSII stream format file.To verify the effectiveness of the light distribution formed by the diffractive optical elements and the realization of white light, simulations based on Field Tracing and Ray Tracing were conducted, confirming the satisfaction of position and luminance requirements at the transformation beam measurement points. Based on this research, it is anticipated that the implementation of adaptive headlights would be possible, enabling the reproduction of luminance contrast and the creation of a simple-structured adaptive headlight system.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.151-155
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• 1998

A new Fabry-Perot tunable filter has been built with simple construction, which does not require any additional aligning and/or beam-confining components for the reduction of the diffraction loss. For this feature, one of the two fibers for the filter is processed to have a concave mirror whose curvature is the same as that of the wavefront of the Gaussian beam from the first fiber. After high reflection coatings, the two fibers are aligned to result in an FP filter whose bandwidth, free spectral range, and insertion loss is 1.47nm, 52nm, 5.6dB respectively.

• Korean Journal of Optics and Photonics
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• v.1 no.1
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• pp.58-64
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• 1990

The flow direction in a glass tube is measured by using a forward scattering dual beam laser Doppler velo$.$ cimeter with an acousto-optic modulator. We can determine the flow direction by measuring the shifted Doppler frequency which is dependent on the order of modulation of the laser beam and the fluid flow direction. Also. an electronic amplification circuit which has a bandwidth of 0 . 300 MHz and a gain of 38 dB is designed and fabricated to amplify the high frequency signal.signal.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.79-86
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• 1999

We propose a new photorefractive demultiplexer(DMUX) for WDM communicaytion system using a wavelength selectivity and demultiplexing properties of a volume holographic grating filters formed in $LinbO_3$ crystal doped with 0.015wt.% Fe. The wavelength selectivity properties of the filter are analyzed and experimentally investigated as a function of the following parameters : the crossing angle of the two writing beams, the reading-beam angle and writing-beam size. In addition, applying these wavelength selectivity properties and the multiplexing technique for recording multiple-exposure filters with equal diffraction efficiency, some preliminary experimental results are presented for use as DMUX.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1353-1361
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• 1992

Holographic optical element(HOE) is fabricated with the properties of lightweight, thin thickness and interconnectivity for free space. Particularly, HOE for optical interconnection and multiple image processing should have a high efficiency and equal spot intensity, Nonlinear equations for 2-dimensional binary phase grating(BPG) structure is solved by computer simulation based on modified Newton method. Computer-generated pattern drawn by plotter is scaled down and translated into the microfilm. After contact printing between the microfilm and silver halide hologram film, phase diffraction grating produces the $5{\times}5$ multiple spots. Experimental results are shown that bleached phase grating has a high efficiency and equal focused beams except central zero order.

• Journal of the Korean Vacuum Society
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• v.3 no.1
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• pp.111-116
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• 1994

본 연구는 CdS, CdSe 분말을 불순물, flux와 혼합하여 질소 분위기에서 소결한 후 전자빔으로 증착하여 적절한 조건에서 열처리 하였다, 이 박막의 결정구조를 X-ray 회절 실험을 통하여 조사하고 제작된 CdS1-xSex 발광 소자의 전기적 특성은 Hall 효과 측정을 이용하고 광학적특성은 광발광 및 광전 류 스펙트럼, 감도, 최대 허용소비전력, 응답시간 등을 분서하교, 발광소자로서의 기능을 검토하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.32-33
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• 2003

자체집광(self-focusing)현상은 대표적인 광학적 비선형 현상중 하나로서, 이를 이용하여 비선형성을 측정하는 연구가 이루어져 왔으며, 근래에는 회절한계이하의 빔 크기를 형성시키기 위하여 자체집광현상을 이용하는 연구가 있어왔다. 이러한 현상에 대해 실험적인 연구와 이론적인 연구가 병행되어 이루어져 왔고, 본 연구에서 다루고자 하는 부분인 이론적인 연구는 주로 non-paraxial BPM을 이용한 연구가 있어왔다. (중략)

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.184-184
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• 2008