• Current Optics and Photonics
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• 제2권1호
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• pp.69-78
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• 2018

This paper presents a precise edge detection algorithm for the critical dimension (CD) measurement of a Thin-Film Transistor Liquid-Crystal Display (TFT-LCD) pattern. The sigmoid surface function is proposed to model the blurred step edge. This model can simultaneously find the position and geometry of the edge precisely. The nonlinear least squares fitting method (Levenberg-Marquardt method) is used to model the image intensity distribution into the proposed sigmoid blurred edge model. The suggested algorithm is verified by comparing the CD measurement repeatability from high-magnified blurry and noisy TFT-LCD images with those from the previous Laplacian of Gaussian (LoG) based sub-pixel edge detection algorithm and error function fitting method. The proposed fitting-based edge detection algorithm produces more precise results than the previous method. The suggested algorithm can be applied to in-line precision CD measurement for high-resolution display devices.

• Journal of the Optical Society of Korea
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• 제6권4호
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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.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.264-268
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• 1990

A guided-wave electro-optic Mach-Zehnder interferometric modulator was fabricated on X-cut LiNbO3 . The channel waveguides were formed by proton diffusion with self-aligned SiO2-cladding. A mach-Zehnder interferometric modulator with arm lengths of 7mm has been fabricated and tested at 0.6328${\mu}{\textrm}{m}$. Its modulation depth with V$\pi$ of only 3.5V was 85% and the 3dB bandwidth was 1.6KHz. For high speed operation, the electrode dimension should be reduced to have smaller R, L, and C.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.270-271
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• 2001

안과 실명 질환의 가장 많은 부분을 차지하는 안구 망막의 실시간 3차원 계측기술은 아직 초보단계에 머물고 있다. 다른 장기나 조직에 비해 3차원계측기술이 늦어진 몇 가지 이유를 들면 다음과 같다. 첫째, 망막이 150$\mu$에서 400$\mu$의 얇은 막이어서 기존의 초음파(ultrasonography), CT(computerized tomography)나 MRI(magnetic resonance image)의 해상력으로는 영상화되지 않는다. 둘째로는 망막이 안구내의 뒤쪽에 위치하여 오직 동공을 통해서만 관찰 가능하여 3차원이 영상화가 어렵다. (중략)

• Current Optics and Photonics
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• 제7권4호
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• pp.419-427
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• 2023

The structural design of an optical-telescope assembly (OTA) for satellite laser ranging (SLR) is conducted in two steps. First, the results of a parametric study of the major design variables (e.g. dimension and shape) of the OTA part are explained, and the detailed structural design of the OTA is derived, considering the design requirements. Among the structural-shape concepts of various OTAs, the Serrurier truss concept is selected in this study, and the collimation of the telescope according to the design variables is extensively discussed. After generating finite-element models for different structural shapes, self-gravity analyses are performed. To minimize the deflection and tilt of the mirror and frame for the OTA under the limited design requirements, a parametric study is conducted according to design variables such as the shapes of the upper and lower struts and the spider vane. The structural features found in the parametric study are described. Finally, the OTA structure is designed in detail to maintain the optical alignment by balancing the gravity deflections of the upper and lower trusses using the optimal combination of the parameters. Additionally, thermal analysis of the optical telescope design is evaluated.

• 대한의용생체공학회:의공학회지
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• 제22권6호
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• pp.527-534
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• 2001

컴퓨터 보조의 3차원 수술지원시스템(CAS. Computer Assisted Surgery)의 3차원 위치검출을 위한 광학식 추적자(Optical Tracker)에서 수술도구에 장착되는 적외선 LED의 좌우 영상을 CCD 카메라로 획득하는 데 있어서 기존의 2개의 프레임그래버를 이용하는 방법을 개선하여 하나의 그래버로 획득하는 방법을 개발하였다 좌우의 영상은 칼라 프레임그래버의 색차신호로 부가되며 이에 관련된 하드웨어 및 검출 알고리즘을 개발하였다 결과적으로 본 연구에서 개발된 방법은 비용이 절감되며 좌우영상의 추출이 빠른 것이 장점이다

• Journal of Astronomy and Space Sciences
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• 제21권4호
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• pp.263-274
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• 2004

한국천문연구원 보현산 천문대(Bohyunsan Optical Astronomical Observatory, BOAO)의 BOES(Bohyunsan Optical Echelle Spectrograph)를 이용하여 2003년 2월 26-27일 이틀간에 걸쳐 BX And의 고분산 관측을 수행하였다. 이 관측을 통하여 얻은 스펙트럼은 총 38개로 위상 $0.1{\sim}0.3$에 이르는 구간을 제외하고는 전위상에 걸쳐 골고루 관측이 이루어졌다. 시선속도를 구하기 위하여 BF(Broadening Function)와 CCF(Cross-Correlation Function)를 이용한 방법 이 모두 사용되었다. CCF를 이용하였을 때는 주성의 시선속도만을 얻은 반면, BF인 경우, 주성과 반성의 시선속도 모두를 잘 결정할 수 있었다. 새로운 시선속도곡선으로부터 주성과 반성의 최대 시선속도를 각각 $K_1=96.1km/s$와 $K_2=196.6km/s$으로 얻었으며, 이를 Bell et al.(1990)의 측광해와 결합하여 BX And의 절대 물리량을 새롭게 결정하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.273-277
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• 2003

A general process of electronic assembly is composed of a series of geometric alignments and bonding/screwing processes. After assembly, the function is tested in a following process of inspection. However, assembly of micro-optic devices requires both processes to be performed in equipment. Coarse geometric alignment is made by using vision and optical function is improved by the following fine motion based on feedback of tunable laser interferometer. The general system is composed of a precision robot system for 3D assembly, a 3D vision guided system for geometric alignment and an optical feedback system with a tunable laser. In this study, we propose a new fast alignment algorithm of micro-optic devices for both of visual and optical alignments. The main goal is to find a fastest alignment process and algorithms with state-of-the-art technology. We propose a new approach with an optimal sequence of processes, a visual alignment algorithm and a search algorithm for an optimal optical alignment. A system is designed to show the effectiveness and efficiency of the proposed method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.317-318
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• 2007

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.531-537
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• 2014

Through-silicon vias (TSVs) are fine, deep holes fabricated for connecting vertically stacked wafers during three-dimensional packaging of semiconductors. Measurement of the TSV geometry is very important because TSVs that are not manufactured as designed can cause many problems, and measuring the critical dimension (CD) of TSVs becomes more and more important, along with depth measurement. Applying white-light scanning interferometry to TSV measurement, especially the bottom CD measurement, is difficult due to the attenuation of light around the edge of the bottom of the hole when using a low numerical aperture. In this paper we propose and demonstrate four bottom CD measurement methods for TSVs: the cross section method, profile analysis method, tomographic image analysis method, and the two-dimensional Gaussian fitting method. To verify and demonstrate these methods, a practical TSV sample with a high aspect ratio of 11.2 is prepared and tested. The results from the proposed measurement methods using white-light scanning interferometry are compared to results from scanning electron microscope (SEM) measurements. The accuracy is highest for the cross section method, with an error of 3.5%, while a relative repeatability of 3.2% is achieved by the two-dimensional Gaussian fitting method.