• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.361-362
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• 2008

• Korean Journal of Optics and Photonics
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• v.2 no.1
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• pp.1-6
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• 1991

This paper describes the theoretical analysis of a diffraction pattern analyzer for the characterization of microscale object fields and a method for obtaining size and size distribution from the measured diffraction pattern of the object fields. For the experimental verification, a typical optical Fourier transform system was set up and calibrated with 2 5$\mu \textrm m$ and 50$\mu \textrm m$ pinholes. The system responses to distilled water droplets, alcohol, glycerin and silicon oil were imaged with vidicon, and the image was processed to determine the size distribution of each liquid particle field. The energy distribution function which is defined as the total intensity of a circular ring in the diffraction pattern was used to determine the dominant particle size of each liquid particle field.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.192-197
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• 1993

반도체 기억소자의 급격한 발전추세에 대응하기 위해서는 노광(exposure) 장비의 증첩정밀도 (overlay accuracy)가 같이 개선되어야 한다. 본 연구에서는 64M ERAM 제조를 목적으로개발된 스텝 퍼(stepper) 시스템의 성능평가 항목 중에서 증첩정밀도에대한 측정방법 및 현재까지의 연구결과를 기술하였다. 제작된 웨이퍼 정렬계는 off-axis 및 TTL 광학계와 이들 정렬신호에 따라 움직이는 웨이 퍼 구동계로 구성되어 있다. off-axis 광학계는 화상처리와 회절의 두 가지 방식이 가능하도록 설계 제작되었으며, TTL 광학계는 dual beam interferometric method를 이용하였다. 본 실험의 결과는 웨이퍼 정렬계의 특성을 평가한 것으로서, 현재까지 off-axis 정렬 방법만으로 얻은 증첩정밀도는 0.26-0.29$\mu$m (m+3 $\sigma$ )이다. 따라서 여기에 이미 제작되어 있는 TLL 정렬광학계를 추가로 사용하면 0.1 $\mu$m 이하의 정밀도에 이를 것으로 예측된다.

• The Optical Journal
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• s.135
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• pp.73-73
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• 2011

한국 광학산업을 상징하는 글로벌 산업단체 한국광학기기협회(www.koia.or.kr)가 2012년 4월11일부터 13일까지 서울 코엑스에서 제1회 광전자 산업전시회를 개최한다. 한국광학기기협회와 케이훼어스(주)가 공동 주최하는 'Photonics Seoul 2012'는 광부품 소재, 레이저 및 레이저응용장비, 광학측정 및 시험분석장비, 정밀영상시스템, IT정보기기, 소프트웨어 및 녹색광산업 분야의 광학장비 및 부품소재 등 광산업 제품을 총 망라하는 대규모 전시회라는 점에서 기대를 모으고 있다. 특히 이 전시회는 국내 광산업체의 비즈니스 활성화를 위해 'SMT/PCB & NEPCON KOREA', 'Printed Electronic & Electronics Materials Show', 'LED Packaging EXPO', 'Film Technology Show' 전시회와 동시 개최되어 전시기간 동안 한자리에서 최신 기술 및 제품 동향은 물론, 다양한 국내외 바이어를 만날 수 있는 기회가 될 것으로 기대된다. 동 전시회에 대한 자세한 사항은 한국광학기기협회 사업추진팀(02-3481-8931)으로 연락하면 된다.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.583-590
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• 2004

The autofocus is one of the important processes in the automated vision inspection or measurements using optical microscopes, because it influences the measuring accuracy. In this paper, we used the confocal microscope configuration based on not a pinhole but a single-mode optical fiber. A single mode fiber has the functions of source and detector by applying the reciprocal scheme. As a result, we acquired a simple system configuration and easy alignment of the optical axis. Also, we embodied a fast autofocus system by acquiring the focus error signal through a source modulation technique. The source modulation technique can effectively reduce physical disturbances compared with objective lens modulation, and it is easily applicable to general optical microscopes. The focus error signal was measured with respect to the modulation amplitude, reflectance of the specimen and inclination angle of the measuring surface. The performance of the proposed autofocus system was verified through autofocusing flat mirror surface. In addition, we confirmed that source modulation rarely degrades the depth resolution by the comparison between the FWHMs of axial response curves.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.684-692
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• 2016

In the manufacturing process of the LQFP/TQFP (Low-profile Quad Flat Package/Thin Quad Flat Package), the requirement of a 3 dimensional inspection is increasing rapidly and a 3D inspection of the shape of a chip has become an important report of quality control. This study developed a 3 dimensional measurement system based on PMP (Phase Measuring Profilometry) for an inspection of the LQFP/TQFP chip and image processing algorithms. The defects of the LQFP/TQFP chip were classified according to the dimensions. The 2 dimensional optical system was designed by the dorm illumination to achieve constant light distribution, In the 3 dimensional optical system, PZT was used for moving 90 degree in phase. The problem of 2 ambiguity was solved from the measured moir? pattern using the ambiguity elimination algorithm that finds the point of ambiguity and refines the phase value. The proposed 3D measurement system was evaluated experimentally.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.294-295
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• 2003

OCT(Optical Coherence Tomography) 기술은 기본적으로 낮은 가간섭성 광원의 빛을 대상물에 주사하여 피대상물의 내부구조에 따른 각종 광학정 수치를 높은 수직 분해능으로 깊이별로 얻어낼 수 있는 기술이다. 현재 많은 생체 연구그룹에서 OCT의 개발과 응용에 대해 적극적인 연구가 진행 중에 있으며, 그 적용분야를 확대하고 있는 추세이다. OCT에 관련된 대표적인 연구분야로서 조직의 미세 단층영상, 혈류 가시화 및 각종 생체조직에 따른 복굴절율 변화 측정 등이 있다.(중략)

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.22-23
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• 2003

광섬유 가변 감쇠기는 광증폭기, add／drop 모듈, Mux／Demux, 광송수신기 등 중요한 광통신 시스템의 입력 및 출력 광신호 레벨을 적절하게 제어하기 위해 요구되는 중요한 소자이다. 가변 감쇠기는 높은 신뢰성, 높은 해상도, 작은 삽입손실, 낮은 편광 및 파장 의존성 손실 등이 요구되어 진다. 가변 광감쇠기는 평면 기판에 형성된 도파로 의 열광학 효과나 전기광학 효과를 이용하는 기법과 MEMS 기술에 기초한 방법이 잘 알려져 있다. (중략)

• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.305-311
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• 2001

The new and simple velocimetry model to be perpendicularly arranged with two optical systems with a projected and reduced rotatable line grating is so proposed as to withstand an external vibration. We measured successfully the various velocities (V_{chop}$) of a chopper by using the new velocimeter. As a result, when rotational angles of projected volume gratings in two optical systems are $\alpha=73^{\circ}$ and $\beta=73^{\circ}$, respectively, we measured successfully the chopper velocities within 1 % accuracy from $V_{chop}=43.52cm/s to 249.36cm/s$. In this new velocimetry, we can determine the confidence of .the system by comparing the z-component of velocity, to be measured in one optical system with $V_z$ to be measured in one optical system with $V_z^'$ to to be measured in another optical system, which should be same.e same.

• Korean Journal of Optics and Photonics
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• v.30 no.3
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• pp.114-119
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• 2019

This paper discusses the development of a Raman lidar system for remote detection and measurement of hydrogen gas by using a photon counter. The Raman signal of the hydrogen gas is very weak and has a very low signal-to-noise ratio. The photon counter has the advantage of improving the signal-to-noise ratio, because it has a discriminator to eliminate the background noise from the Raman signal of the hydrogen gas. Therefore, a small and portable Raman lidar system was developed using a low-power pulsed laser and a photon-counter system to measure the hydrogen gas concentration remotely. To verify the capability of measuring hydrogen gas using the developed photon-counting Raman lidar system, experiments were carried out using a gas chamber in which it is possible to adjust the hydrogen gas concentration. As a result, our photon-counting Raman lidar system is seen to measure a minimum concentration of 0.65 vol.% hydrogen gas at a distance of 10 m.