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15 October 2005 VST active optics system design and status
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This paper is about VST active optics system design, specifications and status. The VST is a modified Ritchey-Chretien wide field Alt-Az telescope with a corrector camera (1 square degree field of view), so when all optical components are correctly aligned, only residual aberrations in whole field are present. The major amounts of these aberrations can be introduced by gravitational and thermo opto-mechanical deformations and mirror misalignments. For these reasons active control of the primary mirror shape and secondary mirror position are required to lessen optical aberrations. The aim of active optics is to correct all optical telescope errors in order to make them small compared with external seeing. The VST is essentially compensated for static or slow frequency deformations and misalignments with a band pass from dc to 1/30 Hz, since the corresponding integration time is sufficient to integrate out the external seeing, giving a round image corresponding to the integrated external seeing quality. VST decentering, coma and defocus are corrected by mean of a secondary mirror position control system (a two-stage hexapode system) and spherical, astigmatism, quad-astigmatism and tri-coma are corrected by mean of M1 mirror shape deformation (axial and radial support system). For optical aberrations and guiding measurement an optical sensing arm has been designed.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
F. Cortecchia, D. Mancini, G. Marra, F. Perrotta, M. Capaccioli, and G. Sedmak "VST active optics system design and status", Proc. SPIE 5962, Optical Design and Engineering II, 596223 (15 October 2005);


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