• Journal of the Optical Society of Korea
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• 제13권4호
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• pp.472-477
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• 2009

A Stokes polarimetry imaging (SPI) system was developed and utilized to detect tendon tears by constructing the degree of linear polarization (DOLP) image maps after linearly polarized light illumination. The micro and partial-thickness tears of turkey tendons were made and imaged by the SPI system at different incident polarization angles (IPA) with different mechanical loads on the tendon. The micro and partial-thickness tendon tears were detected by the DOLP images due to weak birefringence around the tears. The tendon tears were detected by a highest DOLP contrast at longest visible wavelength (Red, 650 ${\pm}$ 50 nm). All polarized images showed modulated DOLP as the incident polarization angle (IPA) was varied. The varying DOLP allowed the optimal detection of the micro and partial-thickness tendon tears at a certain IPA. The SPI system with variable IPA and spectral information can improve the detection of the tendon tears by higher visibility of fiber orientations, and thereby improve diagnosis and treatment of the tendon related injuries.

• 한국전자파학회논문지
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• 제9권5호
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• pp.578-588
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• 1998

본 논문에서는 대표적인 고밀집 도심지역인 서울의 광화문 지역을 대상으로 이중 편파 안테나를 이용한 편파 다이버시티의 전파 전파 성능을 다이버시티 이득과 상호상관계수, 수신 채널의 평균 수신 신호 레벨에 대한 분석 을 통하여 수행하였고 이의 결과를 공간 다이버시티 구조와 비교 분석하였다. 분석 결과, 가시 거리 지역에서는 공간 다이버시티 이득이 편파 다이버시티 이득보다 2 dB 이상 증가하며 전 계를 지면에 대해 $45^{\circ}$로 송신하는 경우보다는 $^90{\circ}$로 송신하는 경우가 다이버시티 이득이 1 dB 큼올 알 수 있었 다. 이와는 대조적으로 비가시 지역에서는 편파다이버시티의 경우가 공간 다이버시티와 대동하거나 운용 환경에 따라서는 오히려 다이버시티 이득이 증가함을 알 수 있었다. 또한 $45^{\circ}$로 송신하는 경우가 $90^{\circ}$로 송신하는 경우보 다는 다이버시티 이득이 최소 1 dB 이상은 커짐을 확인할 수 있었다.

• Journal of the Optical Society of Korea
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• 제17권2호
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• pp.130-135
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• 2013

Based on the extended Huygens-Fresnel principle and generalized Stokes theory, the evolution of polarization properties of beams generated by quasi-homogenous (QH) sources propagating in clear oceanic water was studied by the use of the oceanic turbulence spatial spectrum function. The results show that the beams have similar polarization self-reconstructed behavior under different turbulence conditions in the far field, but if the propagation distance is not long enough, the degree of polarization (DOP) fluctuates with much more complexity than state of polarization (SOP) of QH beams. The self-reconstructed ability of DOP at the special distance in turbulence would get to the best value if the values of coherence of width were chosen suitably, but for SOP, it has no best value.

• Journal of the Optical Society of Korea
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• 제13권4호
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• pp.439-444
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• 2009

Accurate evaluation of polarization characteristics in the integrated optic chip (IOC) for interferometric fiber optic gyroscope was performed. Spatial distribution of optical wavetrains caused by the polarization parameters such as local polarization cross-coupling and polarization rejection coefficient of the IOC were measured utilizing the path-matched optical coherence domain polarimetry (PM-OCDP). With the analytic model deduced from Jones matrix representation, we could accurately identify the polarization characteristics of the IOC. Both degree of measurement error due to the imperfect equipment conditions in PM-OCDP and birefringence of IOC chip were also characterized.

• 천문학회보
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• 제37권2호
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• pp.100.2-100.2
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• 2012

We performed near-IR imaging polarimetry of the $5{\times}9$ fields (${\sim}39^{\prime}{\times}69^{\prime}$) around 30 Doradus in the Large Magellanic Cloud (LMC), using the InfraRed Survey Facility (IRSF). We obtained polarimetry data in the J, H, and Ks bands using the JHKs-simultaneous imaging polarimeter SIRPOL in 2008 December and 2011 December. With the reliable LMC field data which were selected using a bad-data-rejection algorithm, we measured Stokes parameters of point-like sources to derive the degree of polarization and the polarization position angle. We present physical relationship between the three bands using the photometric and the polarimetric properties of the sources.

• 천문학회보
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• 제40권2호
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• pp.36.2-36.2
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• 2015

We report the first detection of linearly polarized emission at an observing wavelength of 350 mum from the radio-loud active galactic nucleus 3C 279. We conducted polarization observations for 3C 279 using the SHARP polarimeter in the Caltech Submillimeter Observatory on 2014 March 13 and 14. For the first time, we detected the linear polarization with the degree of polarization of $13.3%{\pm}3.4%$ (3.9sigma) and the electric vector position angle (EVPA) of $34.^{\circ}7{\pm}5.^{\circ}6$. We also observed 3C 279 simultaneously at 13, 7, and 3.5 mm in dual polarization with the Korean very long baseline interferometry (VLBI) Network on 2014 March 6 (single dish) and imaged in milliarcsecond (mas) scales at 13, 7, 3.5, and 2.3 mm on March 22 (VLBI). We found that the degree of linear polarization increases from 10% to 13% at 13 mm to 350 mum and the EVPAs at all observing frequencies are parallel within < $10^{\circ}$ to the direction of the jet at mas scale, implying that the integrated magnetic fields are perpendicular to the jet in the innermost regions. We also found that the Faraday rotation measures RM are in a range of $-6.5{\times}102{\sim}-2.7{\times}103$ rad m-2 between 13 and 3.5 mm, and are scaled as a function of wavelength:| {RM}| ${\backslash}propto$ {lambda }-2.2. These results indicate that the millimeter and sub-millimeter polarization emission are generated in the compact jet within 1 mas scale and affected by a Faraday screen in or in the close proximity of the jet.

• 천문학회지
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• 제21권2호
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• pp.117-132
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• 1988

Multi-frequency polarization observations of Abell 695 are reported here. The brightest radio source 0838+325, which was previously classified as a wide angled head-tail radio source, is, in the present observations, resolved into two separable sources, a head-tail source 0838+325 AB and a diffuse one 0838+325C. The radio-tail shows high degree of linear polarization(${\sim}50$-25%) along the radio-tail, suggesting that the interaction with its surrounding intracluster medium (ICM) is not highly turbulent. With the present data, thermal particle densities at the locations of these sources are estimated to be n > $10^{-5}\;cm^{-3}$.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2003년도 하계학술대회
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• pp.47-48
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• 2003

A polarization mode dispersion(PMD) compensator with a reponse time less than 200ms has been developed. In our PMD compensator, a reset-free $LiNbO_3$ polarization controller was used in order to reduce the response time, and the compensation algorithm was based on maximization of degree of polarizaiton(DOP).

• 한국광학회지
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• 제14권1호
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• pp.72-79
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• 2003

본 논문에서는 고차 편광모드분산(PMD: polarization-mode dispersion)을 효과적으로 보상하기 위한 방법으로, DOP (degree of polarization)를 1차 PMD 보상을 위한 피드백 신호와 고차 PMD 보상을 위한 feed forward 신호로 사용하는 알고리즘을 제안하였다. 1차 보상이 끝난 후의 DOP값이 남아있는 고차 PMD의 정도를 나타내는 척도로써 인식하여 고차 PMD를 보상하는 시스템이 되겠다. 이러한 시스템은 고차 보상기의 자유도를 1차 보상기의 자유도로 제한하기 때문에 안정적이고 비교적 간단하게 구성할 수 있다는 장점이 있다. 제안된 알고리즘의 성능을 분석하기 위하여 10Gbps NRZ시스템의 전송 모의 실험을 수행하였으며, 그 결과 시스템 다운 시간인 outage probability가 약 세 배 가량 감소되는 것을 확인하였다.

• 천문학회보
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• 제43권1호
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• pp.51.2-51.2
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• 2018

Polarimetry is a powerful technique to investigate the physical properties of surface materials on airless bodies in the solar system. It is known that the degree of linear polarization changes as a function of the phase angle (the angle between Sun-target-Observer). Especially, the dependency of the polarization degree at large phase angle allows us to obtain information related to the particle size and porosity, which is difficult to be determined via other observation techniques (i.e., photometry and spectroscopy). However, despite the advantage, only a few asteroids were observed with polarimetric devices at large phase angles. Here, we present our new polarimetric research of Near-Earth Asteroids (NEAs) observed at the large phase angles. Among the NEAs, we focus on S- and Q-type asteroids, which include: (331471) 1984 QY1, (90075) 2002 VU94, and (66391) 1999 KW4. The observation was conducted using the Pirka 1.6-m Telescope at the Nayoro Observatory of Hokkaido University at the phase angles ${\alpha}{\sim}100degree$, which provides us the maximum polarization degrees of these objects. Considering the observational results together with two objects ((1566) Icarus and (4179) Toutatis) in reference papers [1], [2], we will discuss the implication of the regolith size on their surfaces.