• Title/Summary/Keyword: Mirrors

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Paraboloidal 2-mirror Holosymmetric System with Unit Maginification for Soft X-ray Projection Lithography (연X-선 투사 리소그라피를 위한 등배율 포물면 2-반사경 Holosymmetric System)

  • 조영민;이상수
    • Korean Journal of Optics and Photonics
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    • v.6 no.3
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    • pp.188-200
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    • 1995
  • A design of unit magnification 2-mirror system with high resolution is presented. It is for soft X-ray(wavelength of 13 nm) projection imaging and suitable for preparation of high density semiconductor chip. In general, a holosymmetric system with unit magnification has the advantage that both coma and distortion are completely eliminated. In our holosymmetric 2-mirror system, spherical aberration is addtionally removed by using two identical paraboloidal mirror surfaces and field curvature aberration is also corrected by balancing Petzval sum and astigmatism which depends on the distance between two mirrors, so that the system is a aplanatic flat-field paraboloidal 2-mirror holosymmetric system. This 2-mirror system is small in size, and has a simple configuration with rotational symmetry about optical axis, and has also small central obscuration. Residual finite aberrations, spot diagrams, and diffraction-based MTF's are analyzed for the check of performances as soft X-ray lithography projection system. As a result, the image sizes for the resolutions of$0.25\mum$and $0.18\mum$are 4.0 mm, 2.5 mm respectively, and depths of focus for those are $2.5\mum$, $2.4\mum$respectively. This system should be useful in the fabrication of 256 Mega DRAM or 1 Giga DRAM. DRAM.

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Opto-mechanical Analysis for Primary Mirror of Earth Observation Camera of the MIRIS (MIRIS EOC 주경의 광기계 해석)

  • Park, Kwi-Jong;Moon, Bong-Kon;Park, Sung-Jun;Park, Young-Sik;Lee, Dae-Hee;Ree, Chang-Hee;Nah, Jak-Young;Jeong, Woog-Seob;Pyo, Jeong-Hyun;Lee, Duk-Hang;Nam, Uk-Won;Rhee, Seung-Wu;Yang, Sun-Choel;Han, Won-Yong
    • Korean Journal of Optics and Photonics
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    • v.22 no.6
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    • pp.262-268
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    • 2011
  • MIRIS(Multi-purpose Infra-Red Imaging System) is the main payload of the STSAT-3(Korea Science and Technology Satellite. 3), which is being developed by KASI(Korea Astronomy & Space Institute). EOC(Earth Observation Camera), which is one of two infrared cameras in MIRIS, is the camera for observing infrared rays from the Earth in the range of $3{\sim}5{\mu}m$. The optical system of the EOC is a Cassegrain prescription with aspheric primary and secondary mirrors, and its aperture is 100mm. A ring type flexure supports the EOC primary mirror with pre-loading in order to withstand expected load due to the shock and vibration from the launcher. Here we attempt to use the same mechanism by which a retainer supports the lens. Through opto-mechanical analysis it was confirmed that the EOC primary mirror is effectively supported.

Design of 1.0V O2 and H2O2 based Potentiostat (전원전압 1.0V 산소 및 과산화수소 기반의 정전압분극장치 설계)

  • Kim, Jea-Duck;XIAOLEI, ZHONG;Choi, Seong-Yeol;Kim, Yeong-Seuk
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.2
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    • pp.345-352
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    • 2017
  • In this paper, a unified potentiostat which can measure the current of both $O_2$-based and $H_2O_2$-based blood glucose sensors with low supply voltage of 1.0V has been designed and verified by simulations and measurements. Potentiostat is composed of low-voltage operational transconductance amplifier, cascode current mirrors and mode-selection circuits. It can measure currents of blood glucose chemical reactions occurred by $O_2$ or $H_2O_2$. The body of PMOS input differentional stage of the operational transconductance amplifier is forward-biased to reduce the threshold voltage for low supply voltage operation. Also, cascode current mirror is used to reduce current measurement error generated by channel length modulation effects. The proposed low-voltage potentiostat is designed and simulated using Cadence SPECTRE and fabricated in Magnachip 0.18um CMOS technology with chip size of $110{\mu}m{\times}60{\mu}m$. The measurement results show that consumption current is maximum $46{\mu}A$ at supply voltage of 1.0V. Using the persian potassium($K_3Fe(CN)_6$) equivalent to glucose, the operation of the fabricated potentiostat was confirmed.

Electrical Properties of Al3+ and Y3+ Co-doped SnO2 Transparent Conducting Films (Al3+와 Y3+ 동시치환 SnO2 투명전극 박막의 전기적 특성)

  • Kim, Geun-Woo;Seo, Yong-Jun;Sung, Chang-Hoon;Park, Keun-Young;Cho, Ho-Je;Heo, Si-Nae;Koo, Bon-Heun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.10
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    • pp.805-810
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    • 2012
  • Transparent conducting oxides (TCOs) have wide range of application areas in transparent electrode for display devices, Transparent coating for solar energy heat mirrors, and electromagnetic wave shield. $SnO_2$ is intrinsically an n-type semiconductor due to oxygen deficiencies and has a high energy-band gap more than 3.5 eV. It is known as a transparent conducting oxide because of its low resistivity of $10^{-3}{\Omega}{\cdot}cm$ and high transmittance over 90% in visible region. In this study, co-doping effects of Al and Y on the properties of $SnO_2$ were investigated. The addition of Y in $SnO_2$ was tried to create oxygen vacancies that increase the diffusivity of oxygen ions for the densification of $SnO_2$. The addition of Al was expected to increase the electron concentration. Once, we observed solubility limit of $SnO_2$ single-doped with Al and Y. $\{(x/2)Al_2O_3+(x/2)Y_2O_3\}-SnO_2$ was used for the source of Al and Y to prevent the evaporation of $Al_2O_3$ and for the charge compensation. And we observed the valence changes of aluminium oxide because generally reported of valence changes of aluminium oxide in Tin - Aluminium binary system. The electrical properties, solubility limit, densification and microstructure of $SnO_2$ co-doped with Al and Y will be discussed.

A Study of Roughness Measurement of Rock Discontinuities Using a Confocal Laser Scanning Microscope (콘포컬 레이저 현미경을 이용한 불연속면의 거칠기 측정 연구)

  • Byung Gon Chae;Jae Yong Song;Gyo Cheol Jeong
    • The Journal of Engineering Geology
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    • v.12 no.4
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    • pp.405-419
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    • 2002
  • Fracture roughness of rock specimens is observed by a new confocal laser scanning microscope (CLSM; Olympus OLS1100). The wave length of laser is 488 nm, and the laser scanning is managed by a light polarization method using two galvano-meter scanner mirrors. The function of laser reflection auto-focusing enables us to measure line data fast and precisely. The system improves resolution in the light axis (namely z) direction because of the confocal optics. Using the CLSM, it is Possible to measure a specimen of the size up to $10{\;}{\times}{\;}10{\;}cm$ which is fixed on a specially designed stage. A sampling is managed in a spacing $2.5{\;}\mu\textrm{m}$ along x and y directions. The highest measurement resolution of z direction is $10{\;}\mu\textrm{m}$, which is more accurate than other methods. Core specimens of coarse and fine grained granite are provided. Fractures are artificially maneuvered by a Brazilian test method. Measurements are performed along three scan lines on each fracture surface. The measured data are represented as 2-D and 3-D digital images showing detailed features of roughness. Line profiles of the coarse granites represent more frequent change of undulation than those of the fine granite. Spectral analyses by the fast Fourier transform (FFT) are performed to characterize the roughness data quantitatively and to identify influential frequency of roughness. The FFT results suggest that a specimen loaded by large and low frequency energy tends to have high values of undulation change and large wave length of fracture roughness.

Curvature Linear Equation of a Two-Mirror System with a Finite Object Distance (유한 물체 거리를 갖는 2 반사경계의 곡률 선형 방정식)

  • Lee, Jung-Gee;Rim, Cheon-Seog
    • Korean Journal of Optics and Photonics
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    • v.16 no.5
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    • pp.423-427
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    • 2005
  • In this paper, we propose easily tooling method for Seidel third order aberration, which are not well utilized in actual design process due to the complication of mathematical operation and the difficulty of understanding Seidel third order aberration theory, even though most insightful and systematic means in pre-designing for the initial data of optimization. First, using paraxial ray tracing and Seidel third order aberration theory, spherical aberration coefficient is derived for a two-mirror system with a finite object distance. The coefficient, which is expressed as a higher-order nonlinear equation, consists of design parameters(object distance, two curvatures, and inter-mirror distance) and effective focal length(EFL). Then, the expressed analytical equation is solved by using a computer with numerical analysis method. From the obtained numerical solutions satisfying the nearly zero coefficient condition($<10^{-6}$), linear fitting process offers a linear relationship called the curvature linear equation between two mirrors. Consequently, this linear equation has two worthy meanings: the equation gives a possibility to obtain initial design data for optimization easily. And the equation shows linear relationship to a two-mirror system with a finite object distance under the condition of corrected third order spherical aberration.

Image Enhancement for 3D Shape Measurement Using Large Aperture Projection System (오목거울을 이용한 3차원 형상측정을 위한 모아레 영상 획득 방법)

  • Yoon, Doo-Hyun;Kim, Hak-Il
    • Korean Journal of Optics and Photonics
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    • v.19 no.4
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    • pp.327-333
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    • 2008
  • In general, a lens with large NA makes image quality better. There are many kinds of cheap concave mirrors with large aperture and NA. This paper presents a method that uses a large aperture projection imaging system to enhance the image used for 3D shape measurement. This method makes it possible to enhance reflection uniformity on the object surface and increases SNR (Signal to Noise Ratio). Using a large aperture lens, it is possible to obtain a brighter image, reducing the shading nature in the image boundary, and enhancing the reflection uniformity even on woven surfaces. Because of the exorbitant cost of a large aperture projection lens larger than 150 mm in diameter, a refractive lens was exchanged with a concave mirror resulting in the same optical effect. In experiment, changing NA $0.15{\sim}0.8$, image contrast was enhanced from 46 to 1.33. Incidentally, the effect of the concave mirror was tested successfully through the experiment.

Optical Design of a Subminiature Catadioptric Omnidirectional Optical System with an LED Illumination System for a Capsule Endoscope (LED 조명계를 결합한 캡슐내시경용 초소형 반사굴절식 전방위 광학계의 설계)

  • Moon, Tae Sung;Jo, Jae Heung
    • Korean Journal of Optics and Photonics
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    • v.32 no.2
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    • pp.68-78
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    • 2021
  • A subminiature catadioptric omnidirectional optical system (SCOOS) with 2 mirrors, 6 plastic aspherical lenses, and an illumination system of 6 light emitting diodes, to observe the 360° panoramic image of the inner intestine, is optically designed and evaluated for a capsule endoscope. The total length, overall length, half field of view (HFOV), and F-number of the SCOOS are 14.3 mm, 8.93 mm, 51°~120°, and 3.5, respectively. The optical system has a complementary metal-oxide-semiconductor sensor with 0.1 megapixels, and an illumination system of 6 light-emitting diodes (LEDs) with 0.25 lm to illuminate on the 360° side view of the intestine along the optical axis. As a result, the spatial frequency at the modulation transfer function (MTF) of 0.3, the depth of focus, and the cumulative probability of tolerance at the Nyquist frequency of 44 lp/mm and MTF of 0.3 of the optimized optical system are obtained as 130 lp/mm, -0.097 mm to +0.076 mm, and 90.5%, respectively. Additionally, the simulated illuminance of the LED illumination system at the inner surface of the intestine within HFOV, at a distance of 15.0 mm from the optical axis, is from a minimum of 315 lx to a maximum of 725 lx, which is a sufficient illumination and visibility.

The Limitations of Holocaust Narratives and the Possibility of Healing Narratives Suggested by Smith's Fires in the Mirror ('홀로코스트' 서사의 한계와 스미스의 『거울 속에 반영된 분노』에 제시된 치유 서사의 가능성)

  • Jung, Sun-kug
    • Cross-Cultural Studies
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    • v.43
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    • pp.377-404
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    • 2016
  • In this paper, I intend to focus on the 1991 racial tension and violence portrayed in Anna Devear Smith's book Fires in the Mirror, which was published in book form in 1993. I make use of a series of interviews with many of those involved in the conflicts, which were based on the Jewish Holocaust and the history of African American enslavement. In Crown Heights, the black community and the Jewish community have each suffered terrible losses, but individuals and communities become rhetorically attached to foundational historical traumas that lie at the center of each group's cultural identity rather than try to understand each other's pain. Smith lets this rhetoric dominate Fires in the Mirror by putting contradictory monologues side by side in order to show how discourses on 'slavery' and 'the Holocaust' still have control over specific ethnic communities. My intention is not to delve into the conflict between the Jewish and black communities exclusively. Rather, I attempt to form an understanding of the problems of the critical/theoretical tenets proposed by 'the rhetoric of holocaust,' including the Jewish Holocaust and the black experience of enslavement. Such an understanding will help us see the failure in the theories, illuminating the ways that such rhetoric should have recognized its own violence and helped to forge a new relationship between racism and anti-Semitism. Fires in the Mirror mirrors back to us the ways that 'the Holocaust' betrays the possibility of error to indicate its own susceptibility to blindness. The cracks brought forth by conflicting narratives enable readers to observe wounds being healed and the possibility of new narrative looming up.

Comparison of CH4 Emission by Open-path and Closed Chamber Methods in the Paddy Rice Fields (벼논에서 open-path와 closed chamber 방법 간 메탄 배출량 비교)

  • Jeong, Hyun-cheol;Choi, Eun-jung;Kim, Gun-yeob;Lee, Sun-il;Lee, Jong-sik
    • Korean Journal of Environmental Biology
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    • v.36 no.4
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    • pp.507-516
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    • 2018
  • The closed chamber method, which is one of the most commonly used method for measuring greenhouse gases produced in rice paddy fields, has limitations in measuring dynamic $CH_4$ flux with spatio-temporal constrains. In order to deal with the limitation of the closed chamber method, some studies based on open-path of eddy covariance method have been actively conducted recently. The aim of this study was to compare the $CH_4$ fluxes measured by open-path and closed chamber method in the paddy rice fields. The open-path, one of the gas ($CO_2$, $CH_4$ etc.) analysis methods, is technology where a laser beam is emitted from the source passes through the open cell, reflecting multiple times from the two mirrors, and then detecting. The $CH_4$ emission patterns by these two methods during rice cultivation season were similar, but the total $CH_4$ emission measured by open-path method were 31% less than of the amount measured by closed chamber. The reason for the difference in $CH_4$ emission was due to overestimation by closed chamber and underestimation by open-path. The closed chamber method can overestimate $CH_4$ emissions due to environmental changes caused by high temperature and light interruption by acrylic partition in chamber. On the other hand, the open-path method for eddy covariance can underestimate its emission because it assumes density fluctuations and horizontal homogeneous terrain negligible However, comparing $CH_4$ fluxes at the same sampling time (AM 10:30-11:00, 30-min fluxes) showed good agreements ($r^2=0.9064$). The open-path measurement technique is expected to be a good way to compensate for the disadvantage of the closed chamber method because it can monitor dynamic $CH_4$ fluctuation even if data loss is taken into account.