• Journal of the Optical Society of Korea
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• 제19권5호
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• pp.521-530
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• 2015

Active optics is a key technology for future large-aperture space telescopes. In the design of deformable mirrors for space applications, the design parameter trade-off between the number of regularly configured actuators and the correction capability is essential but rarely analyzed, due to the lack of design legacy. This paper presents a parametric module method for integrated modeling of deformable mirrors with regularly configured actuators. A full design parameter space is explored to evaluate the correction capability and the mass of deformable mirrors, using an autoconstructed finite-element parametric modeling method that utilizes manual finite-element meshing for complex structures. These results are used to provide design guidelines for deformable mirrors. The integrated modeling method presented here can be used for future applied optics projects.

• 천문학회보
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• 제28권2호
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• pp.51-51
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• 2003

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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• pp.25.4-26
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• 2010

We present a three-mirror anastigmat(TMA) optical system for New Generation GOCI. In order to reduce the ghost optimized filter and baffle. By using carefully chosen antireflective coating and tilted filter angle, we fulfilled the design SNR requirement of 1500. We then designed a new entrance baffle and an internal baffle capable of producing the ghost ratio better than 0.01% of the nominal signal. The entrance baffle limits FOV to $0.75^{\circ}$ (E/W) $\times$ $0.60^{\circ}$ (S/N), and prevents the system from strong sun illumination, and the internal baffle prevents stray and scattered ray from entering into the telescope cavity. From these filter and baffle design, we confirmed that the instrument signal to noise ratio can be met with the current conceptual opto-mechanical design.

• 천문학논총
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• 제22권3호
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• pp.55-61
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• 2007

The KASINICS (Korea Astronomy and Space science Institute Near Infrared Camera System) is a ground-based near-infrared (NIR) imaging instrument. KASINICS has offner relay optics to reduce unwanted infrared light. For the offner optics, we adopted an ultra precision machining process which is installed at KBSI (Korea Basics Science research Institute). Since the offner relay optics is made of aluminum 6061 metal material, we did several tests to reach the specification. We found that a 0.497mm radius nose bite and 220m/min machining speed are best tool and condition to make this offner optics with the precision machine. In this paper, we report the technical method of ultra precision machining and results of the KASINICS offner optics.

• 천문학회보
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• 제31권2호
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• pp.54.1-54.1
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• 2006

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2003년도 한국우주과학회보 제12권2호
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• pp.26-26
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• 2003

During fabrication process for the large space optical surfaces, the traditional bound abrasive grinding with bronze bond cupped diamond wheel tools leaves the machine marks and the subsurface damage to be removed by subsequent loose abrasive lapping. We explored a new grinding technique for efficient quantitative control of precision CNC grinding for space optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of resin bond diamond tools. The machining parameters such as grit number, tool rotation speed, work-piece rotation speed, depth of cut and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis methods. The effectiveness of the grinding prediction model was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment details, the results and implications are presented.

• 천문학회지
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• 제29권spc1호
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• pp.425-426
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• 1996

A few optical schemes for the future Russian astrometric satellite ('Struve') are discussed. New optical materials and techniques developed at the Vavilov State Optical Institute are planned to be used for the on-board telescopes. Optical characteristics of the reflecting Schmidt and a three - mirror scheme for the on-board telescopes are compared.

• Journal of the Optical Society of Korea
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• 제20권3호
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• pp.368-380
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• 2016

There is no doubt that adaptive optics (AO) is the most promising method to compensate wavefront disturbance in free space optics communication (FSO). In order to improve the performance of the AO system described by discrete-time linear system model with time-delay and implicit phase turbulent model, new controllers based on a Kalman filter and its extensions are proposed. Based on the standard Kalman filter, we propose a fading memory filter to deal with the ruleless strong interference; sequential and U-D filters are applied to reduce implementation complexity for the embedded controllers. Theoretical analysis and the numerical simulations show that the proposed fading memory filter can upgrade the performance for AO systems in consideration of the unforeseen strong pulse interference, and the sequential and U-D filters perform well compared with a Kalman filter.

• 한국광학회지
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• 제24권3호
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• pp.111-119
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• 2013

대구경 비구면 거울은 대형 천체 망원경이나 고해상도 위성 카메라 등에 사용하는 핵심부품이다. 일반적인 디지털 카메라와 비교하면 매우 크므로 설계 및 제작이 같은 크기의 구면거울보다 훨씬 어렵다. 특히 경량화가 많이 될수록 중력이나 온도변화와 같은 외부의 힘에 의한 변형이 쉽게 발생하기 때문에 이러한 효과를 줄여주는 광기계 설계 및 해석이 더욱 중요해진다. 지상용과 우주용은 사용 환경에 차이가 있어서 설계 요구조건이 달라지고 이에 따라 지지구조물이나 반사경의 경량화 모양 등에 많은 차이가 있다. 본 논문에서는 대구경 비구면 광학기술가운데 가장 어려운 광기계 설계에 관하여 지상용과 우주용으로 나누어 자세히 설명하고자 한다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
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• pp.48.1-48.1
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• 2009

In recent years, many candidates for extra-solar planet have been discovered from various measurement techniques. Fueled by such discoveries, new space missions for direct detection of earth-like planets have been proposed and actively studied. TPF instrument is a fair example of such scientific endeavors. One of the many technical problems that space missions such as TPF would need to solve is deconvolution of the collapsed (i.e. spatially and temporally) spectral signal arriving at the detector surface and the deconvolution computation may fall into a local minimum solution, instead of the global minimum solution, in the optimization process, yielding mis-interpretation of the spectral signal from the potential earth-like planets. To this extend, observational and theoretical understanding on the spectral bio-signal from the Earth serves as the key reference datum for the accurate interpretation of the planetary bio-signatures from other star systems. In this study, we present ray tracing computational model for the on-going simulation study on the Earth bio-signatures. A multi-layered atmospheric model and sea ice variation model were added to the existing target Earth model and a hypothetical space instrument (called AmonRa) observed the spectral bio-signals of the model Earth from the L1 halo orbit. The resulting spectrums of the Earth show well known "red-edge" spectrums as well as key molecular absorption lines important to harbor life forms. The model details, computational process and the resulting bio-signatures are presented together with implications to the future study direction.