• 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.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2435-2439
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• 2005

In case of visual sensing systems with multiple mirrors, systematic errors need to be reduced by the system calibration and the mirror position adjustment in order to enhance system measurement accuracy. In this paper, a self calibration method is presented for a visual sensing system designed to measure the three-dimensional information in deformable peg-in-hole tasks. It is composed of a CCD camera and a series of mirrors including two pyramidal mirrors. By using an image of the inner pyramidal mirror taken by the system, the error parameters of the inner pyramidal mirror could be calibrated or adjusted. Also the influence of the plane mirrors is investigated.

• Smart Structures and Systems
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• 제21권6호
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• pp.777-791
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• 2018

This paper discusses the shape control of deformable mirrors for Adaptive Optics in the dynamic range. The phenomenon of control-structure interaction appears when the mirror becomes large, lowering the natural frequencies $f_i$, and the control bandwidth $f_c$ increases to improve the performance, so that the condition $f_c{\ll}f_i$ is no longer satisfied. In this case, the control system tends to amplify the response of the flexible modes and the system may become unstable. The main parameters controlling the phenomenon are the frequency ratio $f_c/f_i$ and the structural damping ${\zeta}$. Robustness tests are developed which allow to evaluate a lower bound of the stability margin. Various passive and active strategies for damping augmentation are proposed and tested in simulation.

• ETRI Journal
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• 제29권6호
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• pp.817-819
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• 2007

A low-stress organic polymer membrane is proposed as a deformable mirror that can be incorporated into a cellular phone camera to achieve auto focusing without motor-type moving parts. It is demonstrated that our fabricated device has an optical power of 20 diopters and can switch focus in 14 ms. The surface roughness of the organic membrane is measured around 15 nm, less than ${\lambda}$/20 of the visible light. With curve fitting, we found that the actuated membrane is almost parabolic in shape, which leads to less aberration than spherical surfaces. It is suitable for reflective-optics systems.

• 천문학회보
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• 제36권2호
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• pp.132.2-132.2
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• 2011

We are developing Adaptive Optics (AO) system for astronomical use. The He-Ne laser works as an artificial light source. The tip-tilt correction servo is added to our AO system. The tip-tilt term, among the Zernike terms, is the biggest contributor of wavefront deformation caused by atmospheric turbulence at small telescopes. The tip-tilt correction servo consists of a Piezo tip-tilt platform with a mirror, a quadrant photodiode as a tip-tilt sensor, and controllers. The Shack-Hartmann wavefront sensor measures the residual wavefront errors and they are corrected by the MEMS (Micro Electro Mechanical System) deformable mirror. The MEMS deformable mirror allows the compact size at low cost compare to adaptive secondary mirror and other deformable mirrors. As the frame rates of the MEMS deformable mirror is about tens of kHz, the frame rates of the detector in wavefront sensor is the bottleneck of the wavefront correction speed. For faster performance, we replaced a CCD which provides frame rates only 70 Hz with a CMOS with frame rates up to 450 Hz.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 하계학술발표회
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• pp.3-3
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• 2000

Adaptive Optical (AO) technology can compensate for wave-front errors in real-time to improve image and beam quality. The research and development on AO in China began in 1979. In 1980, the first laboratory on AO in China was established in Institute of Optics and Electronics (IOE), Chinese Academy of Sciences (CAS). Since then several AO systems have been built in this Laboratory. The 19-element system is the first AO system in the world ever used in inertial confinement fusion (ICF) facility in our knowledge. It corrects the static error of this large laser engineering. The 21-element system was firstly tested at the 1.2m telescope of Kunming Observatory in 1990 and then up-dated as an IR AO system installed at the 2.16m telescope of Beijing Observatory. The 37-element system was used with a turbulence cell in Laboratory on Atmospheric Optics in Hefei to conduct elementary research on Atmospheric Optics. The 61-element system for astronomical observation is newly developed. It has been successfully installed at the 1.2m telescope of Kunming Observatory and a laser guide star system will be integrated with the system. A compact AO system using our newly developed miniature DM for high resolution ophthalmic imaging of retina is also being built. The key elements of these AO systems, deformable mirrors and fast-steering mirrors, are all developed in this Laboratory. In this talk, the main configurations of these AO systems, some test results as well as the specifications of these active mirrors will be presented.

• 한국게임학회 논문지
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• 제7권1호
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• pp.31-42
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• 2007

피부, 옷 등 실세계의 대부분의 물질들은 반투명한 재질로 되어있고, 부드러운 외양을 띄고 있다. 본 논문에서는 GPU 기반의 계층화 알고리즘을 통해, 양극 확산 (dipole diffusion) 기법에 기반한 표면 내에서의 빛의 산란에 의한 조명을 근사하여 반투명한 재질을 실시간에 렌더링하는 기법을 제안한다. 무수히 많은 수의 픽셀 빛 입자들은 GPU를 활용하여 쿼드트리로 계층화된다. 렌더링될 각 픽셀마다, 많은 빛 입자를 대신하여 좋은 화질로 근사할 수 있는 집합들을 선택하고, 이것을 사용하여 조명을 계산한다. 우리는 또한, 고해상도 이미지를 효율적으로 렌더링하기 위해 공간적 일관성과 early-z 컬링을 이용한 계층적 화면 보간 기법을 소개한다. 이를 위하여, 화면 정보를 GPU 상에서 계층화한다. 우리는 공간적 유사도가 높은 픽셀들을 하나의 픽셀로 렌더링함으로써 적응적으로 보간한다. 실험을 통해 빛 계층화를 통해 반투명한 물체를 실시간에 렌더링할 수 있음을 확인하였다. 화면 보간 기법은 동급 화질에서 렌더링 비용을 $2{\sim}4$배 정도 감소시켰다. 모든 과정은 GPU를 사용한 이미지 공간 상에서 빠르게 수행되며, 어떠한 긴 전처리과정도 필요하지 않는다.