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Proceedings Paper

Performance analysis of the improved seeing limited mode for the Euro50
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Paper Abstract

This paper presents an analysis of the point-spread functions (PSFs), which may be expected in the so-called improved seeing limited mode for the Euro50 (Extremely large telescope with a 50 m aperture). This mode comprises adaptive control of the deformable secondary mirror of the aplanatic Gregorian telescope configuration using guide stars in a wide field. I may result in efficient compensation of turbulence-induced wavefront distortion near the ground layer. The prime goal of the investigations has been to evaluate the performance, in particular the full width at half maximum (FWHM) of the K-band PSFs, as a function of both the guide star field size and the outer scale of the atmospheric fluctuations. For this reason we have adopted a very simple guide star configuration consisting of a circular ring of homogeneously distributed stars. The PSFs are analyzed in the center of the ring. The atmosphere is implemented as the nine layer extended ORM atmosphere described in the paper. One result of the investigations is that the FWHM of the PSFs is very sesitive to the size of the outer scale. For a layer-common outer scale of 20 m, that is slightly less than half of the telescope diameter, the FWHM will stay close to the diffraction limit even for a guide star ring diameter of 10'. This makes the improved seeing limited mode very well suited for a fiber-fed spectrograph located at the F/5 Nasmyth focus of the Euro50.

Paper Details

Date Published: 7 July 2004
PDF: 6 pages
Proc. SPIE 5382, Second Backaskog Workshop on Extremely Large Telescopes, (7 July 2004); doi: 10.1117/12.566270
Show Author Affiliations
Mette Owner-Petersen, Lund Observatory (Sweden)
Alexander V. Goncharov, Lund Observatory (Sweden)


Published in SPIE Proceedings Vol. 5382:
Second Backaskog Workshop on Extremely Large Telescopes
Arne L. Ardeberg; Torben Andersen, Editor(s)

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