MEMS adaptive optics for the Gemini Planet Imager: control methods and validation

Poyneer, Lisa; Dillon, Daren

doi:10.1117/12.772754

Cited by 9 publications

(9 citation statements)

References 16 publications

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“…GPI is a dedicated system for directly imaging and spectroscopically characterizing extrasolar planets. It combines very high order AO (Poyneer & Dillon 2008;Poyneer et al 2014), a diffraction-suppressing coronagraph (Soummer et al 2011), an integral field spectrograph with low spectral resolution but high spatial resolution (Chilcote et al 2012;Larkin et al 2014), and an interferometric calibration wavefront sensor unit, plus an optomechanical support structure and extensive electronics and software infrastructure. First light of GPI occurred on 2013 November 12 UT; its initial performance achieved sufficient contrast for detection of β Pic b in single raw 60 s exposures without any postprocessing.…”

Section: Introductionmentioning

confidence: 99%

Polarimetry With the Gemini Planet Imager: Methods, Performance at First Light, and the Circumstellar Ring Around Hr 4796a

Perrin

Duchêne

Millar-Blanchaer

et al. 2015

ApJ

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165

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We present the first results from the polarimetry mode of the Gemini Planet Imager (GPI), which uses a new integral field polarimetry architecture to provide high contrast linear polarimetry with minimal systematic biases between the orthogonal polarizations. We describe the design, data reduction methods, and performance of polarimetry with GPI. Point spread function subtraction via differential polarimetry suppresses unpolarized starlight by a factor of over 100, and provides sensitivity to circumstellar dust reaching the photon noise limit for these observations. In the case of the circumstellar disk around HR 4796A, GPI's advanced adaptive optics system reveals the disk clearly even prior to PSF subtraction. In polarized light, the disk is seen all the way in to its semi-minor axis for the first time. The disk exhibits surprisingly strong asymmetry in polarized intensity, with the west side 9 times brighter than the east side despite the fact that the east side is slightly brighter in total intensity. Based on a synthesis of the total and polarized intensities, we now believe that the west side is closer to us, contrary to most prior interpretations. Forward scattering by relatively large silicate dust particles leads to the strong polarized intensity on the west side, and the ring must be slightly optically thick in order to explain the lower brightness in total intensity there. These findings suggest that the ring is geometrically narrow and dynamically cold, perhaps shepherded by larger bodies in the same manner as Saturn's F ring.

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Section: Introductionmentioning

confidence: 99%

Polarimetry With the Gemini Planet Imager: Methods, Performance at First Light, and the Circumstellar Ring Around Hr 4796a

Perrin

Duchêne

Millar-Blanchaer

et al. 2015

ApJ

Self Cite

165

142

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“…Research and development interests in this area include opthamological applications, and control systems for large telescopes. [1][2][3][4][5][6][7][8][9][10][11] Here we describe research on the control algorithms for the AO system of the Gemini Planet Imager (GPI). This instrument is designed to image Jovian planets that are one to ten million times fainter than their parent stars, and adaptive optics is key to realizing this objective.…”

Section: Signal Processing For High Precision Control In Adaptive Opticsmentioning

confidence: 99%

Signal and image processing research at the Lawrence Livermore National Laboratory

et al. 2009

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Lawrence Livermore National Laboratory is a large, multidisciplinary institution that conducts fundamental and applied research in the physical sciences. Research programs at the Laboratory run the gamut from theoretical investigations, to modeling and simulation, to validation through experiment. Over the years, the Laboratory has developed a substantial research component in the areas of signal and image processing to support these activities. This paper surveys some of the current research in signal and image processing at the Laboratory. Of necessity, the paper does not delve deeply into any one research area, but an extensive citation list is provided for further study of the topics presented.

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“…For each mode, the temporal PSD is scaled by the magnitude squared of the transfer function for that mode. For a detailed discussion of this technique of influence function compensation in the Fourier domain, see Poyneer and Dillon [18].…”

Section: Estimating Open-loop Temporal Power Spectral Densitiesmentioning

confidence: 99%

Experimental verification of the frozen flow atmospheric turbulence assumption with use of astronomical adaptive optics telemetry

2009

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We use closed-loop deformable mirror telemetry from Altair and Keck adaptive optics (AO) to determine whether atmospheric turbulence follows the frozen flow hypothesis. Using telemetry from AO systems, our algorithms (based on the predictive Fourier control framework) detect frozen flow >94% of the time. Usually one to three layers are detected. Between 20% and 40% of the total controllable phase power is due to frozen flow. Velocity vector RMS variability is less than 0.5 m/s (per axis) on 10-s intervals, indicating that the atmosphere is stable enough for predictive control to measure and adapt to prevailing atmospheric conditions before they change.

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MEMS adaptive optics for the Gemini Planet Imager: control methods and validation

Cited by 9 publications

References 16 publications

Polarimetry With the Gemini Planet Imager: Methods, Performance at First Light, and the Circumstellar Ring Around Hr 4796a

Polarimetry With the Gemini Planet Imager: Methods, Performance at First Light, and the Circumstellar Ring Around Hr 4796a

Signal and image processing research at the Lawrence Livermore National Laboratory

Experimental verification of the frozen flow atmospheric turbulence assumption with use of astronomical adaptive optics telemetry

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