• 한국인쇄학회지
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• 제18권2호
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• pp.41-54
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• 2000

가시광을 선택적으로 반사하는 광 응답성 코레스테릭 액정을 조제하고, 그 선택적 반사파장의 광화학적 변조를 시도함으로서 포토닉스(Photonices) 재료로서의 가능성을 검토했다. 고유의 선택 반사파장의 변조는 아조벤젠 유도체의 트란스(trans)·시스(cis)간의 광이성화에 의해 상전이 온도와 칼라의 변화와 함께 가역적으로 제어되어질 수 있었다. 또한 선택 반사파장의 변화에 수반되는 반사율의 변화는 코레스테릭 액정과 검출광의 광학적 성질에 의해 크게 좌우되어 지고, 반사율의 가역적인 스위칭에 있어서는 검출광에 대한 코레스테릭 액정의 초기 반사파장의 위치는 상반된 스위칭 모드(normal and reverse modes)를 산출하기에 매우 중요한 역할을 담당했다.

• Journal of the Optical Society of Korea
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• 제17권4호
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• pp.317-322
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• 2013

We have proposed and demonstrated a low numerical aperture technique to measure the depth of through silicon vias (TSVs) using white-light scanning interferometry. The high aspect ratio hole like TSV's was considered to be impossible to measure using conventional optical methods due to low visibility at the bottom of the hole. We assumed that the limitation of the measurement was caused by reflection attenuation in TSVs. A novel interference theory which takes the structural reflection attenuation into consideration was proposed and simulated. As a result, we figured out that the low visibility in the interference signal was caused by the unbalanced light intensity between the object and the reference mirror. Unbalanced light can be balanced using an aperture at the illumination optics. As a result of simulation and experiment, we figured out that the interference signal can be enhanced using the proposed technique. With the proposed optics, the depth of TSVs having an aspect ratio of 11.2 was measured in 5 seconds. The proposed method is expected to be an alternative method for 3-D inspection of TSVs.

• 한국물환경학회지
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• 제25권4호
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• pp.547-552
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• 2009

Because of refractory property of light, the travel path of UV light becomes longer than the straight line and shorter solely in water as UV light passes sequentially through air, quartz and water. Note that water significantly absorbs UV light. Hence, UV intensity shall be estimated to be lower when refraction is neglected than it is considered. Reflection is also critical for the design of UV radiation system. While the reflection at the interface of air and quartz is low enough to ignore, it is too high to be ignored at the interface of quartz and water. Assuming constant power, smaller length to width ratio of UV reactor is beneficial and single-lamp system is preferred to multi-lamps. Under the given cross section, optimal lamp positions could be decided. For example of an elliptical reactor with dual lamps, the optimal lamp locations shall be the 1/3 and 2/3 position of the longer axis.

• Journal of Magnetics
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• 제18권3호
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• pp.317-320
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• 2013

We studied the polarization state in an apertureless scanning near-field microscopy (a-SNOM) operating in reflection mode by using three-dimensional Finite-difference Time-domain (FDTD) method. As a result, the electric field around tip apex in the near-field region enhanced four times stronger than the incident light for ppolarization when the tip-sample separation was 10 nm. We find that the p- and s-polarization state is maintained for the scattered light when the probe is perpendicular to the sample. When the probe is not perpendicular to the sample, the polarization state of scattered light will rotate an angle that equals to the inclination angle of probe with p-polarization illumination. On the other hand, the polarization state will not rotate with s-polarization illumination.

• 한국정보과학회논문지:시스템및이론
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• 제28권10호
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• pp.491-498
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• 2001

컴퓨터 그래픽스 분야에서 물체나 장면을 실제 사진처럼 표현할 목적으로 표변 반사 특성에 고나한 많은 연구가 이루어져왔다. 본 논문은 물체의 표면 반산 특성을 구하기 위한 특별한 장비나 복잡한 기하학적인 정보를 필요로 하지 않는 광원 모델링 기법을 제시한다. 이 기법은 영상의 픽셀 밝기정보가 아닌. 카메라로 들어오는 실제 밝기를 나타내는 라디안스 정보를 이용하여 물체 표면의 반사 특성(BRDF)를 측정하는것이 특징이다. 본 논문에서 제안한 광원 모델링을 통하여 다양한 광원에서의 사실적인 장면을 복원할 수 있을 뿐만 아니라 다양한 광원의 조작과 카메라 센서의 노출시간을 자류롭게 조절하는것이 가능하다.

• 한국광학회지
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• 제11권5호
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• pp.317-322
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• 2000

본 논문에서는 두 파장 백색광 간섭법을 이용하여 금속물질을 단차 측정 시 발생하는 오차를 최소화하는 새로운 자가 보정법을 제안한다. 금속 물질의 파장에 대한 위상 변화율은 백색광 간섭무늬의 가시도 정점에 오차로 작용하는데, 자가 보정법은 위상 변화율을 일차 직선으로 가정하고 이를 추출하여 단차 값에 보상한다. 본 자가 보정법은 두 파장 백색광 간섭무늬가 갖는 두 개의 위상 정점과 한 개의 가시도 정점으로부터 위상 변화율 오차를 추출하므로, 별도의 실험이 필요하지 않다. 실험을 통하여 두 개의 금속 물질로 이루어진 단차를 $\pm2nm$ 이내의 오차로 측정함을 보인다.

• 정보저장시스템학회논문집
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• 제6권2호
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• pp.68-73
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• 2010

The interest in acquiring high efficiency solar cells has been steadily increasing due to various advantages such as low-cost installation, pollution free and everlasting energy generation. In order to raise the cell efficiency, there has been a lot of effort to develop effective anti-reflection coatings. In this work, the main objective was to investigate the effects of particle size and annealing temperature of silica anti-reflection coatings to maximize the cell efficiency as well as reliability. It was shown that the light transmittance could be increased by a few percent over a certain range of wavelength using the silica coating. Also, the tribological properties of the coating could be improved through the annealing process, which led to better reliability of the coating.

• 한국광학회지
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• 제27권1호
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• pp.41-46
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• 2016

본 논문은 경면체의 3차원 형상을 측정하기 위한 광학시스템에 관한 것으로, 특히 LED 배열로 이루어진 점광원과 하프미러, 이미지센서로 구성된 비전시스템을 구성하여 광로분석을 수행하고 효과적인 근사화 방법을 제시한다. 실험을 통하여 취득된 영상 내의 점광원의 상대적 위치변화로부터 경면체의 3차원형상의 효과적 추정이 가능함을 보인다.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 동계학술발표회 논문집
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• pp.141-142
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• 2008

In order to develop a simple ray tracing model for simulating the radiation pattern of a LED, the propagation of a ray within the LED capsule was systematically evaluated by considering refraction and reflection from the capsule-air interface, multiple reflection within the capsule, and total internal reflection at the boundary. It was found that concentric ring shapes on the radiation pattern was formed by the rays multiple-reflected from the capsule surface, and that the strength of these rays were decreased rapidly as the number of multiple reflection is increased.

• 전기학회논문지
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• 제56권9호
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• pp.1694-1698
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• 2007

This study suggests a new fluorescence microscope to observe micro-samples within fluorophore in a variety of biomedical fields including the fluorescence analysis of a biochip, such as a DNA micro-array. A fluorescence microscope is a device for irradiating light onto a micro-object, executing an excitation and fluorescence emission process. In this study, it adopts a total internal reflection fluorescence(TIRF) method to excite a whole micro-sample substrate different from an existing way which uses an evanescent wave resulting from a total internal reflection on the micro-sample surface. Suggested TIRF microscope can reduce optical noise and obtain images with higher sensitivity thus obtain precise information about the density, quantity, location, etc. of a flurophore, and can simultaneously process separate images even when plurality of fluorophores having different excitation and fluorescent wavelength ranges is distributed, thus easily obtain information about the fluorophores.