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Proceedings Paper

Realtime speckle sensing and suppression with project 1640 at Palomar
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Paper Abstract

Palomar’s Project 1640 (P1640) is the first stellar coronagraph to regularly use active coronagraphic wavefront control (CWFC). For this it has a hierarchy of offset wavefront sensors (WFS), the most important of which is the higher-order WFS (called CAL), which tracks quasi-static modes between 2-35 cycles-per-aperture. The wavefront is measured in the coronagraph at 0.01 Hz rates, providing slope targets to the upstream Palm 3000 adaptive optics (AO) system. The CWFC handles all non-common path distortions up to the coronagraphic focal plane mask, but does not sense second order modes between the WFSs and the science integral field unit (IFU); these modes determine the system’s current limit. We have two CWFC operating modes: (1) P-mode, where we only control phases, generating double-sided darkholes by correcting to the largest controllable spatial frequencies, and (2) E-mode, where we can control amplitudes and phases, generating single-sided dark-holes in specified regions-of-interest. We describe the performance and limitations of both these modes, and discuss the improvements we are considering going forward.

Paper Details

Date Published: 22 August 2014
PDF: 10 pages
Proc. SPIE 9148, Adaptive Optics Systems IV, 914822 (22 August 2014); doi: 10.1117/12.2056591
Show Author Affiliations
Gautam Vasisht, Jet Propulsion Lab. (United States)
Eric Cady, Jet Propulsion Lab. (United States)
Chengxing Zhai, Jet Propulsion Lab. (United States)
Thomas Lockhart, Jet Propulsion Lab. (United States)
Ben Oppenheimer, American Museum of Natural History (United States)

Published in SPIE Proceedings Vol. 9148:
Adaptive Optics Systems IV
Enrico Marchetti; Laird M. Close; Jean-Pierre Véran, Editor(s)

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