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Wavefront sensing of atmospheric phase distortions at the Palomar 200-in. telescope and implications for adaptive optics

Bloemhof, E. E. and Westphal, J. A. and Ewald, S. P. (1997) Wavefront sensing of atmospheric phase distortions at the Palomar 200-in. telescope and implications for adaptive optics. In: Propagation and Imaging through the Atmosphere. Proceedings of SPIE. No.3125. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, pp. 344-353.

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Major efforts in astronomical instrumentation are now being made to apply the techniques of adaptive optics to the correction of phase distortions induced by the turbulent atmosphere and by quasi-static aberrations in telescopes themselves. Despite decades of study, the problem of atmospheric turbulence is still only partially understood. We have obtained video-rate (30 Hz) imaging of stellar clusters and of single-star phase distortions over the pupil of the 200" Hale telescope on Palomar Mountain. These data show complex temporal and spatial behavior, with multiple components arising at a number of scale heights in the atmosphere; we hope to quantify this behavior to ensure the feasibility of adaptive optics at the Observatory. We have implemented different wavefront sensing techniques to measure aperture phase in wavefronts from single stars, including the classical Foucault test, which measures the local gradient of phase, and the recently-devised curvature sensing technique, which measures the second derivative of pupil phase and has formed the real-time wavefront sensor for some very productive astronomical adaptive optics. Our data, though not fast enough to capture all details of atmospheric phase fluctuations, provide important information regarding the capabilities that must be met by the adaptive optics system now being built for the 200" telescope by a team at the Jet Propulsion Lab. We describe our data acquisition techniques, initial results from efforts to characterize the properties of the turbulent atmosphere at Palomar Mountain, and future plans to extract additional quantitative parameters of use for adaptive optics performance predictions.

Item Type:Book Section
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Ewald, S. P.0000-0002-1567-9154
Additional Information:© 1997 Society of Photo-Optical Instrumentation Engineers (SPIE). Wayne Wailer of Caitech's Campus Computing Organization assisted with frame-grabbing our video data, and Richard Lucinio developed the 8-channel autoguider electronics. Rich Dekany provided helpful insights into various aspects of adaptive optics, and Anand Sivaramakrishnan advised on IRAF analysis of seeing data.
Subject Keywords:astronomy, atmosphere, telescope, turbulence
Series Name:Proceedings of SPIE
Issue or Number:3125
Record Number:CaltechAUTHORS:20200311-161942740
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Official Citation:Eric E. Bloemhof, James A. Westphal, and S. P. Ewald "Wavefront sensing of atmospheric phase distortions at the Palomar 200-in. telescope and implications for adaptive optics", Proc. SPIE 3125, Propagation and Imaging through the Atmosphere, (23 September 1997);
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101888
Deposited By: George Porter
Deposited On:12 Mar 2020 15:25
Last Modified:16 Nov 2021 18:06

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