• Title/Summary/Keyword: Deformable mirror

Search Result 27, Processing Time 0.025 seconds

A Cooled Deformable Bimorph Mirror for a High Power Laser

  • Lee Jun-Ho;Lee Young-Cheol;Kang Eung-Cheol
    • Journal of the Optical Society of Korea
    • /
    • v.10 no.2
    • /
    • pp.57-62
    • /
    • 2006
  • Adaptive optics (AO) has been applied in various fields including astronomy, ophthalmology and high power laser systems. An adaptive optics system for a high power laser is not significantly different from other AO systems in the point of configuration except that high energy absorbed by the deformable mirror distorts the deformable mirror surface and so degrades system performance. Currently we are researching a bimorph deformable mirror for beam cleaning of a high power class laser. The bimorph mirror was considered to have 99% reflective coating and 1% absorption. So this paper first presents the temperature profiles and corresponding thermal distortions of the bimorph mirror faceplate when the mirror is under a high power lasing for 10 seconds. The analysis was accomplished by the use of finite difference and finite element computer programs to generate the element arrays, calculate the temperature profiles, and determine the structural deformations. Then this paper proposes an 'embedded wafer' type water-cooling system with derived cooling parameters.

Development a simple MEMS-based astronomical adaptive optics system at laboratory

  • Yu, Hyung-Jun;Park, Yong-Sun;Chae, Jong-Chul;Yang, Hee-Su
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.36 no.2
    • /
    • pp.132.2-132.2
    • /
    • 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.

  • PDF

A study on the actuator arrays of a deformable mirror for adaptive optics (적응광학계 변형거울의 구동기 배열에 따른 성능 변화 연구)

  • 엄태경;이완술;윤성기;이준호
    • Korean Journal of Optics and Photonics
    • /
    • v.13 no.5
    • /
    • pp.442-448
    • /
    • 2002
  • In the earth telescope for space observation, the adaptive optical (AO) system that immediately compensates atmospheric turbulence is helpful to get high-resolution images. An adaptive optics for earth telescopes is very attractive, since the Earth telescopes can be made at lower costs and have larger optical apertures than space telescopes. Generally. in order to remove the wavefront error produced by atmospheric turbulence, a deformable mirror, whose surface shape changes in a controllable way in response to a drive signal, is used. The characteristics and patterns of actuators are very important for the effective control of a deformable mirror. The mirror surface shape deformed by one actuator is defined as an influence function and the deformable mirror can be effectively modeled and designed using this influence function. In this paper. by simplifying the actual influence function obtained by FEM analyses into the Gaussian function and introducing the coupling coefficient between actuators, the influence function is constructed. The proper coupling coefficient of the target system can be obtained by performance analyses of a deformable mirror for various coupling coefficients. Using the constructed influence function, the deformable mirror with equally spaced triangular and square actuator patterns is analyzed for various spacings and an effective actuator pattern is proposed.

A Circular Bimorph Deformable Mirror for Circular/Annulus/Square Laser Beam Compensation

  • Lee J.H.;Lee Y.C.;Cheon H.J.
    • Journal of the Optical Society of Korea
    • /
    • v.10 no.1
    • /
    • pp.23-27
    • /
    • 2006
  • We are studying the application of an adaptive optics system to upgrade the beam quality of a laser. The adaptive optics (AO) system consists of a bimorph deformable mirror, a Shack-Hartmann sensor and a control system. In most AO applications, the beam aperture is considered to be circular. However, in some cases such as laser beams from unstable resonators, the beam apertures are annulus or a holed-rectangle. In this paper, we investigate how well a bimorph deformable mirror of ${\Phi}120\;mm$ clear aperture can compensate phase distortions for three different beam configurations; 1) ${\Phi}120\;mm$ circular aperture, 2) ${\Phi}100\;mm$ annulus aperture with a ${\Phi}20\;mm$ hole and 3) $70\;mm{\times}70\;mm$ square aperture with a hole of $30\;mm{\times}30\;mm$. This study concludes that the bimorph mirror, which might be considered as a modal controller, can compensate tilt, defocus, coma and astigmatism, and spherical aberration for all three beams.

A Pyramidal Mirror System Calibration Method for Robotic Assembly

  • Kim, J.Y.;Kang, D.J.;Kim, M.S.;Ha, J.E.;Lho, T.J.;Yoon, J.S.
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 2005.06a
    • /
    • pp.2435-2439
    • /
    • 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.

  • PDF

Method for the Assembly of a High-density Multi-channel Deformable Mirror for High Energy Lasers (고에너지 레이저용 고밀집 다채널 실리콘-카바이드 변형거울의 정밀 조립 방법)

  • Hyug-Gyo Rhee;Sunho Cho;Sihyun Kim;Jaehyun Lee;Pilseong Kang
    • Korean Journal of Optics and Photonics
    • /
    • v.35 no.4
    • /
    • pp.170-174
    • /
    • 2024
  • A laser beam propagating in free space can be negatively affected by atmospheric turbulence. To overcome this and correct the wavefront error of the laser beam itself, a deformable mirror (DM), which is a key component of adaptive optics, is widely used. In this paper, a novel precision assembling method is suggested for a multi-channel high-density DM. The material of the mirror sheet of the DM is silicon carbide (SiC), and the actuator is a stacked-type lead-magnesium-niobate (Pb(Mg1/3Nb2/3)O3; PMN). To connect the mirror sheet and each actuator, a flexure is inserted. The flexure can make the DM operate with full strokes without the failure of adhesive. A series of jigs were designed and applied in order to assemble these three parts (the mirror sheet, actuators, and flexures) precisely. After assembly, the performance of the DM was also checked.

Control-structure interaction in piezoelectric deformable mirrors for adaptive optics

  • Wang, Kainan;Alaluf, David;Mokrani, Bilal;Preumont, Andre
    • Smart Structures and Systems
    • /
    • v.21 no.6
    • /
    • pp.777-791
    • /
    • 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.

Polymer Deformable Mirror for Optical Auto Focusing

  • Wang, Jen-Liang;Chen, Tyng-Yow;Liu, Chingwei;Chiu, Chen-Wei Edward;Su, Guo-Dung John
    • ETRI Journal
    • /
    • v.29 no.6
    • /
    • pp.817-819
    • /
    • 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.

  • PDF

Laboratory test of MEMS based astronomical adaptive optics

  • Yu, Hyung-Jun;Park, Yong-Sun;Chae, Jong-Chul;Yang, Hee-Su
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.36 no.1
    • /
    • pp.65.1-65.1
    • /
    • 2011
  • We built a simple Adaptive Optics (AO) system at laboratory. This AO system is a step toward developing AO system for astronomical use. In this step, the AO system consists of He-Ne laser as a artificial light source, wavefront sensor, MEMS (Micro electro mechanical system) type deformable mirror and several lenses. MEMS deformable mirror allows the compact system at low cost and the only several mm sized collimated beam. We made Shack-Hartmann wavefront sensor using a lenslet array and a fast frame CCD. Its performance is verified using an artificial phase disturber and noting the movement of spot images by the lenslet array. The frame rate of the driving software is about 70 fps, depending on the control parameters. The characteristics of MEMS deformable mirror was measured which includes the voltage-to-deflection relation, influence function, and cross-talk. The total system is operated under closed-loop control for the artificial phase disturber and the wavefront is found to be compensated successfully.

  • PDF