Effects of differential wavefront sensor bias drifts on high contrast imaging
Naru Sadakuni, Bruce A. Macintosh, David W. Palmer, Lisa A. Poyneer, Claire E. Max, Dmitry Savransky, Sandrine J. Thomas, Andrew Cardwell, Stephen Goodsell, Mar… 展开作者
Naru Sadakuni, Bruce A. Macintosh, David W. Palmer, Lisa A. Poyneer, Claire E. Max, Dmitry Savransky, Sandrine J. Thomas, Andrew Cardwell, Stephen Goodsell, Markus Hartung, Pascale Hibon, Fredrik Rantakyrö, Andrew Serio, with the GPI team
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8 pages, 7 figures. Proceedings of the SPIE, 9148-217
The Gemini Planet Imager (GPI) is a new facility, extreme adaptive optics (AO), coronagraphic instrument, currently being integrated onto the 8-meter Gemini South telescope, with the ultimate goal of directly imaging extrasolar planets. To achieve the contrast required for the desired science, it is necessary to quantify and mitigate wavefront error (WFE). A large source of potential static WFE arises from the primary AO wavefront sensor (WFS) detector's use of multiple readout segments with independent signal chains including on-chip preamplifiers and external amplifiers. Temperature changes within GPI's electronics cause drifts in readout segments' bias levels, inducing an RMS WFE of 1.1 nm and 41.9 nm over 4.44 degrees Celsius, for magnitude 4 and 11 stars, respectively. With a goal of $<$2 nm of static WFE, these are significant enough to require remedial action. Simulations imply a requirement to take fresh WFS darks every 2 degrees Celsius of temperature change, for a magnitude 6 star; similarly, for a magnitude 7 star, every 1 degree Celsius of temperature change. For sufficiently dim stars, bias drifts exceed the signal, causing a large initial WFE, and the former periodic requirement practically becomes an instantaneous/continuous one, making the goal of $<$2 nm of static WFE very difficult for stars of magnitude 9 or fainter. In extreme cases, this can cause the AO loops to destabilize due to perceived nonphysical wavefronts, as some of the WFS's Shack-Hartmann quadcells are split between multiple readout segments. Presented here is GPI's AO WFS geometry, along with detailed steps in the simulation used to quantify bias drift related WFE, followed by laboratory and on sky results, and concluded with possible methods of remediation.
Modal estimation of high-order wavefront drifts on coronagraphic testbeds for high-contrast direct imaging of exoplanets
Massachusetts Institute of Technology（麻省理工学院）；California Institute of Technology（加州理工学院）；Jet Propulsion Laboratory（喷气推进实验室）；Rensselaer Polytechnic Institute（伦斯勒理工学院）；Space Telescope Science Institute（太空望远镜科学研究所）；University of California, Santa Cruz（加州大学圣克鲁兹分校）；LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS（巴黎天文台LESIA，PSL大学，索邦大学，巴黎西岱大学，法国国家科学研究中心）；Lowell Center for Space Science and Technology, University of Massachusetts（马萨诸塞大学洛厄尔空间科学与技术中心）；The University of Alabama in Huntsville（阿拉巴马大学亨茨维尔分校）；Princeton University（普林斯顿大学）
Laboratory demonstration of low order wavefront control using light reflected off the vortex coronagraph
California Institute of Technology（加州理工学院）；Jet Propulsion Laboratory, California Institute of Technology（喷气推进实验室，加州理工学院）；Trinity College Dublin, the University of Dublin（都柏林三一学院，都柏林大学）
High-contrast imager for complex aperture telescopes (HiCAT): 8. Dark zone demonstration with simultaneous closed-loop low-order wavefront sensing and control
A Statistical Framework for Utilization of Simultaneous Pupil Plane and Focal Plane Telemetry for Exoplanet Imaging, Part II: The Science Camera Image as a Function of the Wavefront Sensor Field
Mid-order wavefront control for exoplanet imaging: preliminary characterization of the segmented deformable mirror and Zernike wavefront sensor on HiCAT
Characterization of sensitivity and responses of a 2-element prototype wavefront sensor for millimeter-wave adaptive optics attached to the Nobeyama 45 m telescope
我们报告的结果的原型波前传感器的性能表征毫米自适应光学（MAO）安装在Nobeyama 45米射电望远镜。微弧氧化是实现未来大口径亚毫米波望远镜的关键部件，如大型亚毫米波望远镜（LST）或阿塔卡玛大口径亚毫米波望远镜（AtLAST）。然而，微弧氧化的困难在于，在孔径上以~10 μ m的精度实时感测波前变形。我们的波前传感器工作在20 GHz的测量主镜表面的某个位置到放置20 GHz相干接收器的焦点之间的无线电路径长度。与2元件的原型，我们采样的两个位置上的主镜表面（在半径为5米和16米）在10 Hz的采样率。然后，通过对两个光路进行微分，得到两个位置之间的多余光程长度（EPL）。EPL的功率谱密度示出三个分量：低频漂移（1/f^n）、振荡和白噪声。比较了不同风况下的EPL测量结果，发现前两种现象可能是由望远镜结构的风荷载引起的。白噪声的功率对应于EPL测量中8 μ m的1西格玛统计误差。8 um r.m.s.对于LST和AtLAST所需的镜面精度（~20-40 μ m r.m.s.）而言是重要的，这表明，我们的技术也是有用的，为未来的大口径亚毫米望远镜。
Slow focus sensor for the Keck I laser guide star adaptive optics system using focal plane wavefront sensing
Aix-Marseille Univ, CNRS, CNES, LAM（艾克斯-马赛大学）；Macquarie University（麦考瑞大学）；Faculdade de Engenharia da Universidade do Porto（波尔图大学工程学院）；Center for Astrophysics and Gravitation, Instituto Superior Técnico（天体物理学与引力中心，里斯本高等理工学院）；W.M. Keck Observatory（W.M.凯克天文台）；DOTA, ONERA, Université Paris Saclay（ONERA DOTA实验室，巴黎萨克雷大学）；Space ODT
On the Effects of Pointing Jitter, Actuators Drift, Telescope Rolls and Broadband Detectors in Dark Hole Maintenance and Electric Field Order Reduction
