• Title, Summary, Keyword: lens space

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Lens Surgeries along the n-twisted Whitehead Link

  • Kadokami, Teruhisa;Maruyama, Noriko;Shimozawa, Masafumi
    • Kyungpook Mathematical Journal
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    • v.52 no.3
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    • pp.245-264
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    • 2012
  • We determine lens surgeries (i.e. Dehn surgery yielding a lens space) along the n-twisted Whitehead link. To do so, we first give necessary conditions to yield a lens space from the Alexander polynomial of the link as: (1) n = 1 (i.e. the Whitehead link), and (2) one of surgery coefficients is 1, 2 or 3. Our interests are not only lens surgery itself but also how to apply the Alexander polynomial for this kind of problems.

Divide Knot Presentation of Knots of Berge's Sporadic Lens Space Surgery

  • Yamada, Yuichi
    • Kyungpook Mathematical Journal
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    • v.60 no.2
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    • pp.255-277
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    • 2020
  • Divide knots and links, defined by A'Campo in the singularity theory of complex curves, is a method to present knots or links by real plane curves. The present paper is a sequel of the author's previous result that every knot in the major subfamilies of Berge's lens space surgery (i.e., knots yielding a lens space by Dehn surgery) is presented by an L-shaped curve as a divide knot. In the present paper, L-shaped curves are generalized and it is shown that every knot in the minor subfamilies, called sporadic examples of Berge's lens space surgery, is presented by a generalized L-shaped curve as a divide knot. A formula on the surgery coefficients and the presentation is also considered.

Athermal Elastomeric Lens Mount for Space Optics

  • Kihm, Hag-Yong;Yang, Ho-Soon;Moon, Il-Kweon;Lee, Yun-Woo
    • Journal of the Optical Society of Korea
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    • v.13 no.2
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    • pp.201-205
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    • 2009
  • We investigated the optimum adhesive thickness for athermalizing an elastomeric lens mount in our space optics application. Theoretical results were compared with finite element solutions using two different models; discrete circular pads and discrete circular pads with columns filling the insertion holes reflecting the reality. A noticeable difference between their optimal thicknesses was observed, and physical interpretation revealed the uncertainty of prevailing athermal equations. A pilot sample was made to check our results and thermo-optical stress was assessed using an interferometer after isothermal load. This study presented insight into preliminary design guidance in elastomeric lens mounting.

PRELIMINARY OPTICAL DESIGN OF MIRIS, MAIN PAYLOAD OF STSAT-3 (과학기술위성3호 주탑재체 MIRIS의 광학계 시험설계)

  • Yuk, I.S.;Jin, H.;Lee, S.;Park, Y.S.;Lee, D.H.;Nam, U.W.;Park, J.H.;Han, W.Y.;Lee, J.W.
    • Publications of The Korean Astronomical Society
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    • v.22 no.4
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    • pp.201-209
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    • 2007
  • We have preliminarily designed two infrared optical systems of the multi-purpose infrared camera system (MIRIS) which is the main payload of STSAT-3. Each optical system consists of a Cassegrain telescope, a field lens and a 1:1 re-imaging lens system that is essential for providing a cold stop. The Cassegrain telescope is identical for both of two infrared cameras, but the field correction lens and re-imaging lens system are different from each other because of different bands of wavelength. The effective aperture size is 100mm in diameter and the focal ratio is f/5. The total length of the optical system is 300mm and the position of the cold stop is 25mm from the detector focal plane. The RMS spot size is smaller than $40{\mu}m$ over the whole detector plane.

Optics of the light-weight and foldable telescope based on the Fresnel lens

  • Yu, Hyungjoon;Park, Yong-Sun;Chung, Haeun
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.1
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    • pp.57.3-58
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    • 2016
  • We analyze an optical system of a telescope based on Fresnel type objective lens as suggested by Hyde (1999). The Fresnel objective lens can be thin, light-weight and foldable, and therefore it is possible to develop a space telescope with an aperture larger than that of traditional telescopes. Moreover a lens, whatever it is either Fresnel type or conventional, allows much larger fabrication tolerances. We design a medium-sized telescope adopting Fresnel lens as an objective lens for use in space and possibly on the ground. The well-known chromatic aberration of the Fresnel primary lens is corrected by a field lens and another Fresnel lens using Schupmann method. An additional lens is used for forming images. We analyze the chromatic and off-axis aberrations of the proposed system analytically and suggest methods for the minimization of off-axis aberrations and for the operation in wider spectral range. We also conduct ray tracing and optimize the whole optical system with commercial software. Finally we present the design parameters of a telescope with an aperture of 0.5 to 1 meters, enabling diffraction limited operation for a moderate field of view about 10 arc-minutes.

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Effect of Particle Contamination on Objective Lens in a CD-ROM Drive on Laser Diode Power and Photo Diode RF Signal (CD-ROM 드라이브의 대물렌즈 입자오염이 Laser Diode의 Power와 Photo Diode의 RF Signal에 미치는 영향)

  • Pae, Yang-Il;Hwang, Jung-Ho
    • Proceedings of the KSME Conference
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    • pp.1429-1434
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    • 2003
  • A number of dust particles are intruded into ODD(Optical disk drive) due to the flow caused by disk rotation and are adhered to a lens or disk surface. The space between the disk and the lens is being reduced. Someone indicates the problems of this drive that are relatively small data storing capacity and slow access time. In recent, the problems of this optical disk drive mentioned above are being solved by adding the speed of the disk's revolution, making the actuator high-speed or light, and making the beam spot size smaller than making the space narrow between disk and lens. These particle contamination affects seriously RF Signal, readout signal in an ODD. Especially, the affected parts by a particle contamination in an ODD's readout signal are objective lens and media.

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Rigorous Analysis of Viewing Zone for 3D Display with Electric-field-driven Liquid Crystal Lens (액정 전계 렌즈 기반 3차원 디스플레이 장치의 엄정한 시청영역 분석)

  • Kim, Tae-Hyeon;Kim, Bong-Sik;Park, Woo-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.8
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    • pp.494-498
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    • 2016
  • In this paper, we proposed the 3-dimenstional (3D) analysis for calculating the optical characteristics of an autostereoscopic display with electric field driven liquid crystal (ELC) lens. From 3D analysis considering the slanting of lens, we calculate the cross-talk of each images and the distortion of viewing zone. Using geometric opics and extended Jones matrix method (EJMM), phase retardation of ELC lens according to position is calcuated and then optical path difference in 3D space considering tilt and azimuth angle of incident light is gotten. Then, intensity distribution is presented in the space. Through camparing the intensity distribution using ideal lens with the ELC lens, we identify the noise and image distortion of ELC lens. As a result, this analysis is expected to provide optimum design conditions for realistic and rigorous 3D display with ELC lens.

OGLE-2017-BLG-1049: ANOTHER GIANT PLANET MICROLENSING EVENT

  • Kim, Yun Hak;Chung, Sun-Ju;Udalski, A.;Bond, Ian A.;Jung, Youn Kil;Gould, Andrew;Albrow, Michael D.;Han, Cheongho;Hwang, Kyu-Ha;Ryu, Yoon-Hyun;Shin, In-Gu;Shvartzvald, Yossi;Yee, Jennifer C.;Zang, Weicheng;Cha, Sang-Mok;Kim, Dong-Jin;Kim, Hyoun-Woo;Kim, Seung-Lee;Lee, Chung-Uk;Lee, Dong-Joo
    • Journal of The Korean Astronomical Society
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    • v.53 no.6
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    • pp.161-168
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    • 2020
  • We report the discovery of a giant exoplanet in the microlensing event OGLE-2017-BLG-1049, with a planet-host star mass ratio of q = 9.53 ± 0.39 × 10-3 and a caustic crossing feature in Korea Microlensing Telescope Network (KMTNet) observations. The caustic crossing feature yields an angular Einstein radius of θE = 0.52 ± 0.11 mas. However, the microlens parallax is not measured because the time scale of the event, tE ≃ 29 days, is too short. Thus, we perform a Bayesian analysis to estimate physical quantities of the lens system. We find that the lens system has a star with mass Mh = 0.55+0.36-0.29 M⊙ hosting a giant planet with Mp = 5.53+3.62-2.87 MJup, at a distance of DL = 5.67+1.11-1.52 kpc. The projected star-planet separation is a⊥ = 3.92+1.10-1.32 au. This means that the planet is located beyond the snow line of the host. The relative lens-source proper motion is μrel ~ 7 mas yr-1, thus the lens and source will be separated from each other within 10 years. After this, it will be possible to measure the flux of the host star with 30 meter class telescopes and to determine its mass.