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Proceedings Paper

Cone effect in astronomical adaptive optics system investigated by a pure numerical simulation
Author(s): Hai-Xing Yan; Han-Ling Wu; Shu-Shan Li; She Chen
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Paper Abstract

It is well-known that cone effect or focus anisoplanatism is produced by the limited distance of a laser guide star (LGS) which is created within the Earth atmosphere and consequently located at a finite distance from the observer. In this paper, the cone effect of the LGS for different vertical profiles of the refractive index structure constant is numerically investigated by using a revised computer program of atmospheric propagation of optical wave and an adaptive optics (AO) system including dynamic control process. According to the practice, the overall tilt for the tilt-correction mirror is obtained from a natural star and the aberrated wavefront for phase correction of the deformable mirror is obtained from a LGS in our numerical simulation. It is surprisingly found that the effect of altitude of the LGS on the AO phase compensation effectiveness by using the commonly-available vertical profiles of C2n and the lateral wind speed in the atmosphere is relatively weak, and the cone effect for some C2n profiles is even negligible. It is found that the cone effect does not have obvious relationship with the turbulence strength, however, it depends on the vertical distribution profile of apparently. On the other hand, the cone effect depends on the vertical distribution of the lateral wind speed as well. In comparison to a longer wavelength, the cone effect becomes more obvious in the case of a shorter wavelength. In all cases concerned in this paper, an AO system by using a sodium guide star has almost same phase compensation effectiveness as that by using the astronomical target itself as a beacon. Effect of dynamic control process in an AO system on the cone effect is studied in this paper for the first time within our knowledge.

Paper Details

Date Published: 25 August 2005
PDF: 12 pages
Proc. SPIE 5903, Astronomical Adaptive Optics Systems and Applications II, 59030U (25 August 2005); doi: 10.1117/12.616110
Show Author Affiliations
Hai-Xing Yan, Institute of Mechanics, CAS (China)
Han-Ling Wu, Institute of Mechanics, CAS (China)
Shu-Shan Li, Institute of Mechanics, CAS (China)
She Chen, Institute of Mechanics, CAS (China)

Published in SPIE Proceedings Vol. 5903:
Astronomical Adaptive Optics Systems and Applications II
Robert K. Tyson; Michael Lloyd-Hart, Editor(s)

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