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Proceedings Paper

Real time atmospheric turbulence compensation: implementing dedicated hardware
Author(s): Peter Linde; Anders Astrom; Guang-Ming Dai; Robert Forchheimer; Arne L. Ardeberg
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Paper Abstract

We discuss a device for real time compensation of image quality deterioration induced by atmospheric turbulence. The device will permit ground based observations with very high image resolution. We propose an instrument with two channels. One is an ordinary image detection channel, while the other uses a Hartmann-Shack wavefront detector to measure image degradation. This information is obtained in the form of a set of lenslet focus shifts, each corresponding to the local tilt of the wavefront. Through modeling, the entire wavefront is reconstructed. Consequently, we can estimate the optical transfer function and its corresponding point spread function. Through convolution techniques, the distorted image can subsequently be restored. Thus, image correction is performed in software, eliminating the need for expensive live optics designs. Due to the nature of atmospheric turbulence, detection and correction have to be made with 50 - 100 frames per second. This implies a need for very high computing capacity. A study of the mathematical operations involved has been made with special emphasis on implementation in the hardware architecture known as radar video image processor (RVIP). This hardware utilizes a high degree of parallelism. Results available show that RVIP together with complementary units provide the necessary high-speed computing capacity. The detection system in both channels must meet very high demands. We mention high quantum efficiency, fast readout at low noise levels and a wide spectral range. A preliminary investigation evaluates suitable detectors. ICCDs are so far the most promising candidates.

Paper Details

Date Published: 21 March 1997
PDF: 8 pages
Proc. SPIE 2871, Optical Telescopes of Today and Tomorrow, (21 March 1997); doi: 10.1117/12.269099
Show Author Affiliations
Peter Linde, Lund Observatory (Sweden)
Anders Astrom, Linkoeping Univ. (Sweden)
Guang-Ming Dai, Washington Univ. (United States)
Robert Forchheimer, Linkoeping Univ. (Sweden)
Arne L. Ardeberg, Lund Observatory (Sweden)

Published in SPIE Proceedings Vol. 2871:
Optical Telescopes of Today and Tomorrow
Arne L. Ardeberg, Editor(s)

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