• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.05a
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• pp.321-325
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• 2006

원호(round) > 다각형(polygon) $\fallingdotseq$ W형의 순서로 나타났다. 초기 반응속도가 가장 높은 원호 형을 기준으로 반사율이 다른 반사판을 사용한 결과 반사율 정도에 따른 성능차이는 적은 것으로 나타났다. 반사판의 크기가 커질수록 반사되는 광세기와 RhB 탈색율이 증가하지만 38 cm이상의 반사판에서의 광 세기 증가율은 감소되는 것으로 나타났으며, 최적 반사판 크기는 38 cm 인 것으로 사료되었다.

• Progress in Medical Physics
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• v.7 no.1
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• pp.25-35
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• 1996

Optical measurements of turbid biological tissue have provided a means to study tissue metabolism, tissue blood perfusion and blood oxygenation non-invasively. We used the red light of 660nm and infrared of 880nm to measure the blood fractional volume and oxygen saturation of biological tissue. In vivo reflectance data were obtained the physiological change from the deep tissue in human subject. The data evaluation was assessed by examining the slopes of the plotter index for the changes in oxygen saturation and blood fraction volume. The index is the natural logarithm of the ratio of reflected light intensity from measured medium to reference intensity at each wavelength. According to the experimental results, oxygen index changes significantly in the muscle of calf during exercise.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.324-325
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• 2003

광섬유 브래그 격자 센서(Fiber Brags Grating Sensor： FBG Sensor)는 여타 광섬유 센서와 같이 가볍고 저렴하며 주위의 전자기적 잡음에 무관한 장점과 더불어 측정대상이 반사광의 파장변화이므로, 광섬유 연결부나 실험장치들에 의해 생기는 광 손실이나 잡음에 대해서 강인한 측정을 할 수 있다. 그리고 파장변화가 변형률이나 온도변화에 선형적으로 나타나므로, 센서로서 많은 연구가 진행되고 있다. 특히, 구조물의 내부에 삽입하여 구조물 스스로 외부의 환경변화를 감지하여 필요한 동작을 수행하는 지능형 구조물(Smart Structure)에 적합한데, 이를 위해선 구조물의 여러 지점을 측정해야 하므로, 브래그 격자 여러개를 한 시스템에서 사용하는 다중화(Multiplexing)가 필수적이다. (중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.612-618
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• 2016

The aim of this study is to investigate the effects of stray light originating from the blue-light blocking lens on the quality of the image. After designing the ideal spectacle lens, anti-reflection spectacle lens without internal reflection, anti-reflection spectacle lens with internal reflection, and blue-light blocking lens with internal reflection, the light intensity distribution and stray light distribution were derived. The designed spectacle lenses are meniscus lenses with a refractive power of 0.00 D, refractive index of 1.56, and a radius of 155.15 mm. The peaks of reflectance of the 4 types of blue-light blocking lenses are in the range between 430 nm and 440 nm, and their reflectances are 5%, 10%, 15%, and 20%, respectively. According to the analysis results, as the reflectance of the blue-light blocking lens increases, the light intensity in the center of the lens decreases and the intensity of the stray light in the center-periphery and periphery of the lens increases. This trend appeared to intensify with increasing reflectance of the blue-light blocking lenses. Because the increase in the reflectance of the blue-light blocking lens degrades the quality of the image by increasing the intensity of the stray light in the center-periphery and periphery of the lens, its reflectance needs to be adjusted by varying the blue-light blocking ratio and the luminous transmittance, in order to diminish the level of visual discomfort.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.1
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• pp.6-12
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• 2010

Fiber optic sensor using fiber Bragg grating(FBG) probes is used for monitoring strain and temperature distributed on the wide surfaces of large structures. In this paper, in order to use many FBG probes in one optical fiber line, we propose a complex multiplexing technology which is composed of two techniques, one is time division multiplexing and another is wavelength division multiplexing. However, we only investigate the characteristics of time division multiplexing because FBG sensors basically can be operated by wavelength division multiplexing. We calculate the optimal reflectivities and the lengthwise location of five FBG probes in serial connection in order to obtain the unique reflected intensities from the FBG probes. We fabricate five FBG probes with the reflectivities of 13%, 16%, 25%, 40% and 80%, which are determined by the theoretical calculation, and observe the signal reflected from each FBG in the time domain from the experiment. There are differences between experimental and theoretical results caused by the signal noise and the differences of reflectivities of FBG probes. But the experimental results shows the reflected signals of five FBG probes which prove the availability of complex multiplexing.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.241-246
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• 2021

In this paper, hydrogenated amorphous silicon(a-Si:H) grating coupler with distributed Bragg reflector(DBR) is proposed to achieve high-efficiency nanophotonic radiator for Light Detection and Ranging(LiDAR) application. The DBR reduces downward leakage of the optical field below the grating region. As a result, the far-field intensity shows about 1.4 times stronger, compared to the common grating coupler without the DBR.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.80-80
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• 2008

바이오 센서 응용 연구에 많이 사용되는 금(Au) 나노 입자를 이용한 국소 표면 플라즈몬 공명(Localized Surface Plasmon Resonance, LSPR)에 의한 산란광을 검출하는데 주로 이용되는 암시야(dark field) 현미경 검출 방식에 관한 전산모사를 통하여 입사광의 입사 방식에 따른 산란광 세기를 정량적으로 분석하였다. 전산모사 기법으로는 국소 표면 플라즈몬 공명의 동역학적인 현상을 모사할 수 있는 유한차분시간영역(Finite Difference Time Domain, FDTD) 기법을 이용하였는데, 이러한 기법이 암시야 현미경 전산 모사에 유효함을 우선적으로 검증하였다. 암시야 현미경 검출 방식의 모사에서 입사 광원의 반사 입사 방식과 투과 입사 방식을 비교하였고, 각각의 방식에 서 입사광의 입사각에 따른 산랑광 세기를 계산하였다. 이러한 전산모사를 통하여 프리즘을 통한 내부 전반사(Total Internal Reflection, TIR) 방식에서 입사 광원의 임계각 근처에서 많이 발생하는 에바네슨트 장(evanescent field)을 결합하는 경우 산란광 세기가 증가함을 관찰하였고, 이러한 세기의 변화를 프레넬(Fresnel) 방정식에 의해 계산된 에바네슨트 장의 세기 분포와 비교 분석하였다.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.31-36
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• 1994

We present a structure of a reflective Fabry-Perot etalon with nonlinear Kerr material (Kerr FP etalon), and report the polarization conversion and the optical bistability of polarization conversion. A device proposed has high polarization conversion ratio, 100% or so, and good/broad optical bistablity for input pump intensity.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.31-37
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• 2000

In order to color analyze of in Farnsworth Test Panel D-15 using a Protan, Deutan and Tritan test, we introduced the CIE system so that measured the reflectance light spectrum intensity in the 380~780 nm wavelength regions. The color difference of Panel D-15 was depended on the intensity of reflectance ratio in the 400~450 nm, 500~600 nm and more than 650 nm wavelength regions. From the reflectance spectra, we obtained the tristimulus X, Y, Z values, the $L^*a^*b^*$ and $L^*ab$ values of the 3-Dimension CIELAB system in a complement plane and light-darkness axis, the $U^*V^*$ values and the x, y values of chromaticity coordinates.

• Korean Journal of Optics and Photonics
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• v.32 no.4
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• pp.172-179
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• 2021

A near-normal-incidence ellipsometer (NNIE) is suggested as an optical critical dimension (OCD) measurement system that is highly sensitive to the bottom defect of a sample with high-aspect-ratio structured patterns. Incident light passes through a polarizer and a phase retarder in sequence, and the reflected light from the sample also passes through them, but in reverse order. The operating principle of this NNIE, where a single polarizer and a single phase retarder are shared by the incident and reflected light, is studied, and a method to determine the ellipsometric constants from the measured intensities at proper combinations of the azimuthal angles of polarizer and retarder is presented.