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Proceedings Paper

Evaluation of a maximum a-posteriori slope estimator for a Hartmann wavefront sensor
Author(s): Troy B. Van Caster; Byron M. Welsh; Michael C. Roggemann
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Paper Abstract

The Hartmann sensor is a popular wavefront sensor (WFS) for measuring the wavefront gradient in the pupil of an adaptive optical telescope. Conventional methods for estimating the wavefront slope within each WFS subaperture rely on a centroid computation of the subaperture detector irradiance distribution. The centroid computation is equivalent to a first moment calculation. A maximum a-posteriori (MAP) slope estimator improves on the conventional centroid estimator by taking advantage of priori knowledge of the subaperture wavefront slope statistics and total irradiance falling on the subaperture array. In order to derive a closed form solution for the MAP estimator, several assumptions were made in a previously published paper. These assumptions include: infinitely small pixels on the subaperture detector arrays, no read noise in the detection process, and on irradiance spillover between adjacent subapertures. By implementing the Hartmann WFS and MAP estimator in a detailed computer simulation, the performance of the MAP estimator was evaluated using realizable WFS parameters. The simulation shows that even when the assumptions used to derive the MAP slope estimator are relaxed, the MAP estimator outperforms the conventional subaperture centroid estimator.

Paper Details

Date Published: 3 November 1998
PDF: 11 pages
Proc. SPIE 3433, Propagation and Imaging through the Atmosphere II, (3 November 1998); doi: 10.1117/12.330224
Show Author Affiliations
Troy B. Van Caster, Air Force Institute of Technology (United States)
Byron M. Welsh, Air Force Institute of Technology (United States)
Michael C. Roggemann, Michigan Technological Univ. (United States)

Published in SPIE Proceedings Vol. 3433:
Propagation and Imaging through the Atmosphere II
Luc R. Bissonnette, Editor(s)

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