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19 results on '"Gerard, Benjamin L."'

8. Deployment of focal plane WFS technologies on 8-m telescopes: from the Subaru SPIDERS pathfinder, to the facility-class GPI 2.0 CAL2 system

Author

Schreiber, Laura, Schmidt, Dirk, Vernet, Elise, Marois, Christian, Lardière, Olivier, Thompson, William, Singh, Garima, Johnson, Adam, Hardy, Tim, Fitzsimmons, Joeleff, Gerard, Benjamin L., Sivanandam, Suresh, Thibault, Simon, Savransky, Dmitry, Bradley, Colin, Jensen-Clem, Rebecca, Demers, Mathieu, Fu, Qiang, Heidrich, Wolfgang, and N'Diaye, Mamadou

Published
2022
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11. High-speed Focal Plane Wave Front Sensing with an Optical Chopper

Author

Gerard, Benjamin L., Dillon, Daren, Cetre, Sylvain, and Jensen-Clem, Rebecca

Abstract

Focal plane wave front sensing and control is a critical approach to reducing noncommon path errors between a conventional astronomical adaptive optics (AO) wave front sensor (WFS) detector and a science camera. However, in addition to mitigating noncommon path errors, recent focal plane wave front sensing techniques have been developed to operate at speeds fast enough to enable “multi-WFS” AO, where residual atmospheric errors are further corrected by a focal plane WFS. Although a number of such techniques have been recently developed for coronagraphic imaging, here we present one designed for noncoronagraphic imaging. Utilizing conventional AO system components, this concept additionally requires (1) a detector imaging the focal plane of the WFS light source and (2) a pupil plane optical chopper device that is the noncommon path to the first WFS and is synchronized to the focal plane imager readout. These minimal hardware requirements enable the temporal amplitude modulation to resolve the sine ambiguity of even wave-front modes for low, mid, and high wave front spatial frequencies. Similar capabilities have been demonstrated with classical phase diversity by defocusing the detector, but such techniques are incompatible with simultaneous science observations. This optical chopping technique, however, enables science imaging at up to 50% duty cycle. We present both simulations and laboratory validation of this concept on SEAL, the Santa Cruz Extreme AO Laboratory testbed.

Published
2023
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15. Focal Plane Wavefront Sensing with the FAST TGV Coronagraph

Author

Gerard, Benjamin L. and Marois, Christian

Abstract

The continual push to directly image exoplanets at lower masses and closer separations orbiting around bright stars remains limited by both quasi-static and residual adaptive optics aberration. In previous papers we have proposed a modification of the self-coherent camera (SCC) design to address both of these limitations, called the Fast Atmospheric SCC Technique (FAST). In this paper we introduce an additional modification to the FAST focal plane mask design, including the existing Tip/tilt and Gaussian components and adding a charge four Vortex (TGV) component. In addition to boosting SCC fringe signal-to-noise ratio (S/N) as in our previous design, we show that the FAST TGV mask is also optimized to reach high contrast at separations closer to the star. In this paper we use numerical simulations to consider the performance improvement on correcting quasi-static aberration using this new mask compared to the previously proposed Tip/tilt+Gaussian mask. Using active deformable mirror control to generate a calibrated half dark hole improves contrast by a factor of about 200 at 2-5 ?/Dand up to a factor of 10 at 5-20 ?/D. The new methodology presented in this paper, now simultaneously considering both contrast and fringe S/N, opens the door to a new ideology of coronagraph design, where the coronagraph is now considered in duality as both a diffraction attenuator and a wavefront sensor.

Published
2020
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16. Revised astrometric calibration of the Gemini Planet Imager

Author

De Rosa, Robert J., Nguyen, Meiji M., Chilcote, Jeffrey, Macintosh, Bruce, Perrin, Marshall D., Konopacky, Quinn, Wang, Jason J., Duchêne, Gaspard, Nielsen, Eric L., Rameau, Julien, Ammons, S. Mark, Bailey, Vanessa P., Barman, Travis, Bulger, Joanna, Cotten, Tara, Doyon, Rene, Esposito, Thomas M., Fitzgerald, Michael P., Follette, Katherine B., Gerard, Benjamin L., Goodsell, Stephen J., Graham, James R., Greenbaum, Alexandra Z., Hibon, Pascale, Hung, Li-Wei, Ingraham, Patrick, Kalas, Paul, Larkin, James E., Maire, Jérôme, Marchis, Franck, Marley, Mark S., Marois, Christian, Metchev, Stanimir, Millar-Blanchaer, Maxwell A., Oppenheimer, Rebecca, Palmer, David, Patience, Jennifer, Poyneer, Lisa, Pueyo, Laurent, Rajan, Abhijith, Rantakyrö, Fredrik T., Ruffio, Jean-Baptiste, Savransky, Dmitry, Schneider, Adam C., Sivaramakrishnan, Anand, Song, Inseok, Soummer, Remi, Thomas, Sandrine, Wallace, J. Kent, Ward-Duong, Kimberly, Wiktorowicz, Sloane, and Wolff, Schuyler

Published
2020
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