• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.198-198
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• 2010

The low-k SiOCH thin films were prepared by CCP-PECVD method using BTMSM(Bis-trimethylsilylmethane) precursors deposited on p-Si wafer. The structural complexity originate the complex refractive constants of the films, and resulted the elliptical polarization of the incident linearly polarized light source of Xe-ramp in the range from 190nm to 2100nm. Phase difference and amplitude ratio between s wave and p wave propagating through SiOCH thin film was studied. After annealing, the amplitude of p wave was reduced more than s wave, and phase difference between p and s wave was also reduced.

• International Journal of Air-Conditioning and Refrigeration
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• 제8권2호
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• pp.11-22
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• 2000

Holographic interferometric tomography can provide reconstruction of instantaneous three-dimensional gross flow fields. The technique however confronts ill-posed reconstruction problems in practical applications. Experimental data are usually limited in projection and angular scanning when a field is captured instantaneously or under the obstruction of test models and test section enclosures. An algorithm, based on a series expansion method, has been developed to improve the reconstruction under the ill-posed conditions. A three-dimensional natural convection flow around two interacting isothermal cubes is experimentally investigated. The flow can provide a challenging reconstruction problem and lend itself to accurate numerical solution for comparison. The refractive index fields at two horizontal sections of the thermal plume with and without an opaque object are reconstructed at a limited view angle of 80$\circ$. The experimental reconstructions are then compared with those from numerical calculation and thermocouple thermometry. It confirms that the technique is applicable to reconstruction of reasonably complex, three-dimensional flow fields.

• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.925-931
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• 2009

This paper reports a preliminary experimental investigation and characterization of an optical fiber-based submersion sensor system for applications in water flooding and leakage. The sensor system comprises a multi-mode fiber spliced with fiber Bragg grating and an intensity-based interrogator. Submersion tests were conducted in water-air and Glycerin-air environments. By the refractive index of the fiber-probe surrounding materials, the reflectance and the detecting power level is determined. When the probe is dipped into the water, the optical output power dramatically decreases from -7.5dBm to -17.5dBm. But, the center of Bragg wavelength is not affected in spite of external material changes. Temporal response characteristics of the sensor system is investigated to verify the real-time reaction. When the probe is immersed into the liquid, there is no transition time.

• 한국표면공학회지
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• 제52권4호
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• pp.211-226
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• 2019

Optical thin films were deposited by using a reactive pulsed DC magnetron sputtering method with a high density plasma(HDP). In this study, the effect of sputtering process conditions on the microstructure and optical properties of $SiO_2$, $TiO_2$, $Nb_2O_5$ thin films was clarified. These thin films had flat and dense microstructure, stable stoichiometric composition at the optimal conditions of low working pressure, high pulsed DC power and RF power(HDP). Also, the refractive index of the $SiO_2$ thin films was almost constant, but the refractive indices of $TiO_2$ and $Nb_2O_5$ thin films were changed depending on the microstructure of these films. Antireflection films of $Air/SiO_2/Nb_2O_5/SiO_2/Nb_2O_5/SiO_2/Nb_2O_5/Glass$ structure designed by Macleod program were manufactured by our developed sputtering system. Transmittance and reflectance of the manufactured multilayer films showed outstanding value with the level of 95% and 0.3%, respectively, and also had excellent durability.

• 한국광학회지
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• 제7권1호
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• pp.37-43
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• 1996

횡자장하에서 Zeeman 안정화된 He-Ne 레이저를 광원으로 한 두 종류의 공기굴절율 측정용 간섭계를 설계.제작하였다. 제작된 간섭계는 레이저 광속이 진공조와 기체조를 2번 혹은 4변 지나도록 설계하여 분해능을 향상시켰으며 그 경로가 진공조를 중심으로 대칭적으로 지나도록 설계하여 열적인 변형 및 기계적인 진동에 강한 특성을 갖도록 하였다. 진공조와 기체조 사이의 광로차를 위상각 검출 방식의 heterodyne 간섭계로 측정하므로써 homodyne 간섭계에서 발생되는 간섭무늬 해석 오차를 최소화시켜 공기굴절율 측정의 정확도를 향상시켰다. 제작된 두 굴절율계를 이용하여 여러 조건에서 공기굴절율을 측정한 결과 평균값에서의 상호 편차는 $2\times10^{-8}$ 이하였으며 Edlen공식을 이용한 굴절율계와의 편차는 $1\times10^{-7}$ 이하였다.

• Current Photovoltaic Research
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• 제10권4호
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• pp.95-100
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• 2022

Solar cell is a device that converts photon energy into electrical energy. Therefore, absorption of solar spectrum light is one of the most important characteristics to design the solar cell structures. Various methods have emerged to reduce optical losses, such as textured surfaces, back contact solar cells, anti-reflection layers. Here, the anti-reflection coating (ARC) layer is typically utilized whose refractive index value is between air (~1) and silicon (~4) such as SiN_x layer (~1.9). This research is to print a material called polydimethylsiloxane (PDMS) to form a double anti-reflection layer. Light with wavelength in the range of 0.3 to 1.2 micrometers does not share a wavelength with solar cells. It is confirmed that the refractive index of PDMS (~1.4) is an ARC layer which decreases the reflectance of light absorption region on typical p-type solar cells with SiN_x layer surface. Optimized PDMS printing with analyzing optical property for cell structure can be the effective way against outer effects by encapsulation.

• 한국광학회지
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• 제13권2호
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• pp.105-112
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• 2002

전자총을 사용하여 증착한 보통(conventional) Nb$_2$O$_{5}$ 박막과 Ar 이온빔 보조 증착(ion beam assisted deposition, IBAD)한 Nb$_2$O$_{5}$ 박막의 광학적, 물리적 특성을 조사하여 IBAD의 효과에 대해 연구하였다. IBAD Nb$_2$O$_{5}$ 박막과 보통 Nb$_2$O$_{5}$ 박막의 진공-공기간 반사 스펙트럼과 박막 단면의 SEM 측정 결고, IBAD Nb$_2$O$_{5}$ 박막은 보통 박막에 비해 조밀한 박막으로 증착되었으며, 분광 광도계를 이용하여 포락선 방법으로 구한 IBAD Nb$_2$O$_{5}$ 박막의 평균 굴절률은 보통 Nb$_2$O$_{5}$ 박막 보다 증가하고, 소멸계수는 감소하였다. 이는 IBAD에 의한 이온빔 충격으로 Nb$_2$O$_{5}$ 박막의 미세구조가 변화하여 조밀도가 증가하였기 때문으로 판단된다. 주입 산소 양이 증가함에 따라 IBAD Nb$_2$O$_{5}$ 박막과 보통 Nb$_2$O$_{5}$ 박막의 평균 굴절률과 소멸계수는 모두 감소하는 경향을 보였으며, IBAD Nb$_2$O$_{5}$ 박막은 이온빔 전류 밀도가 증가함에 따라 평균 굴절률이 증가하였다. 보통 Nb$_2$O$_{5}$ 박막과 IBAD Nb$_2$O$_{5}$ 박막은 모두 불균일 굴절률을 나타냈으며, IBAD Nb$_2$O$_{5}$ 박막은 이온빔 전류 밀도가 증가할수록 굴절률의 불균일도는 증가하였다. 증착된 Nb$_2$O$_{5}$ 박막은 XRD 측정 결과 모두 비정질이었으며, IBAD에 의해 박막의 결정 구조는 변하지 않았다.

• 한국광학회지
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• 제20권3호
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• pp.182-188
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• 2009

완충용액과 분석시료의 확산으로 발생하는 측정 오차를 최소화하기 위하여 공기주입 장치와 공기제거 장치를 설치한 표면 플라즈 몬 공명 타원계측기(surface plasmon resonance ellipsometer: SPRE)를 새로이 제안하고 이를 제작하였다. SPRE에서 완충용액과 분석시료간의 상호 확산은 분석시료의 농도를 변화시켜 굴절률 측정에 영향을 주고, 이 결과 생체분자 물질의 접합 특성이 명확하게 나타나지 않는다. 이러한 SPRE의 측정 장치에 공기를 주입하는 장치를 추가로 설치하여 두 용액의 확산을 막고, 특히 불필요한 공기가 채널 내부로 유입되어 생기는 잡음신호를 없애기 위하여 공기제거 장치를 사용함으로써 신뢰성 있는 SPRE의 측정 결과를 얻을 수 있음을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1801-1807
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• 2001

In multiphase flne the bubble size and velocity. To achieve this, one of approaches is to utilize laser phase-Doppler anemometry. However, it was found that the second order refraction has great impact on PDA sizing method when the relative refractive index of media is less than one. In this paper, the problem of second order refraction is investigated and a model of phase-size correlation to eliminate the measurement errors is introduced for bubble sizing. As a result, the model relates the assumption of single scattering mechanism in conventional phase-Doppler anemometry. The results of simulations based on this new model by using Generalized Lorenz Mie Theory (GLMT) are compared with those based on the conventional method. An optimization method for accurately sizing air-bubble in water has been suggested.

• Bulletin of the Korean Chemical Society
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• 제26권6호
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• pp.947-951
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• 2005

Rotating compensator multichannel spectroscopic ellipsometry has been employed to determine the optical functions of various liquids used in chemistry. We attempted three different measurement configurations: (1) air-liquid interface, (2) prism-liquid interface, and (3) liquid-sample interface. In prism-liquid interface, we found that the prism surface had roughness and it should be considered in analysis for accurate results. In liquidsample interface, we had much higher reflection, better sensitivity, and less limitation compared to the other two configurations when crystalline silicon was used as reference sample. We discuss the merit of each configuration and present the optical functions of various liquids. Also we demonstrate Bruggeman effective medium theory to determine the optical properties of mixed liquid.