• Journal of the Optical Society of Korea
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• v.6 no.4
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• pp.180-184
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• 2002

In this study, we investigated mask errors, photo errors with attenuated phase shift mask and off-axis illumination, and etch errors in dry etch conditions. We propose that total process proximity correction (TPPC), a concept merging every process step error correction, is essential in a lithography process when minimum critical dimension (CD) is smaller than the wavelength of radiation. A correction rule table was experimentally obtained applying TPPC concept. Process capability of controlling gate CD in DRAM fabrication should be improved by this method.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.82-86
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• 1990

A camera type optical bench system equipped with a lens collimator and an image analyzer is fabricated to measure the equivalent focal length and distortion of lenses. This system is automatized by the computer which controls stepping motors. A nodal slide optical bench system equipped with an off axis reflective collimator is fabricated and improved by using rotating arms and air bearing system. distortion measurement on a wide angle lens using the camera method and the nodal slide method is reported. Defocusing error in the distortion measurement with the nodal slide optical bench is analyzed and improved by iteration method to search the correct image point.

• Progress in Medical Physics
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• v.1 no.1
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• pp.69-73
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• 1990

Dosimetric measurement of an asymmetric collimator system was performed, using water phantom system for 4MV X-ray linear accelerator. We have studied the system of dose calculation with those measured result. We compared the field size factor and the percent depth dose for asymmetric collimator to those factor for symmetric fields. The results show that we can use symmetric field data directly within 1% error, if we consider the off axis ratio(OAR).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.107-107
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.9-12
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• 1991

방전가열형 구리증기레이저의 비축형 불안정공진기를 사용하여 레이저의 빔발산각을 안정공진기의 경우에 비해 25배 (200 $\mu$rad) 까지 줄였다. 이때 불안정공진기의 배율 M 은 50 이었으며, 평균출력은 안정공진기를 사용할 경우에 비해 53 %를 얻었다. 또한, M이 8.5 일 때 (750 $\mu$rad) 평균출력은 안정공진기의 94% 까지 도달하였다.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.162-167
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• 1991

홀로그램 광학소자(holographic optical element)의 일종인 holographic collimating lens(HCL)를 최적 설계하였으며, 중크롬산 젤라틴 필름을 사용하기 최적 설계치에 따라 HCL을 제작하였고 그 성능을 평가하였다. off-axis 방식의 holographic zone plate (HZP) 구조를 채택하였으며, 기록광과 재생광의 파장 차이에 의한 색수차를 최소화시키기 위해 유한 광선 추적법과 감쇠 최소자승법으로 최적 설계하였다. Dipping 법으로 제작된 중크롬산 젤라틴(Dichromated Gelatin, DCG) 필름을 기록 매질로 사용하여 HCL을 제작하였으며 회절광의 집적도를 측정하여 그 성능을 평가하였다.

• Proceedings of the Optical Society of Korea Conference
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• 1990.07a
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• pp.87-93
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• 1990

Estimation and collection of the suitable recording materials are important for the fabrication of the holographic optical elements. In this study, silver halide emulsion, photoresist and dichromated gelatin are selected as a recording materials to investigate the properties and processing methods. Some parameters which affect the diffraction efficiencies of the holographic optical elements (HOE) are presented. As an example of the HOE, the results of design and the fabrication method of the off axis 12P hologram lens are also presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.629-634
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• 2000

This System is developed for the estimation of the Camera Lens Resolution. Signal data proportional to light intensity is obtained and sampled from the 2D CCD. Based on the measured signal. the MTF charateristcs of a camera lens are measured. We could measure the sagittal and tangential MTF in the on and off-axis at the same time. The automatic measurig methods for optimal image plane, magnification, and best marginal direction of test lens are presented.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.76.2-76.2
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• 2010

We report the extended far-ultraviolet (FUV) halo of NGC 891 above the galactic plane. The FUV intensity distribution is well described by two exponential components, one with the scale height of ~0.34 kpc and the other of ~2.3 kpc. The extraplanar FUV halo is traceable up to > 5 kpc. The FUV halo is attributable to scattered-off starlight by extraplanar dust. Using Monte-Carlo radiative transfer simulations, the FUV intensity distribution along the minor axis is found to be well modeled with two dust comonents. Its implications are discussed.

• Journal of the Optical Society of Korea
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• v.10 no.4
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• pp.178-183
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• 2006

An in-line phase-shifting digital holographic microscopy system was constructed by inserting a conventional microscope in the object arm of a Mach-Zehnder interferometer. It was used to measure the three dimensional shape of a micro Fresnel lens. It was also shown that both the lateral and the axial resolutions of the in-line phase-shifting system using a self-calibration algorithm were superior to those of the best off-axis system.