16 August 2000 Conceptual design for a NIR prime focus camera for the ESO 3.6
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We present in this paper a preliminary design of a near IR wide field imager for the prime focus of the ESO 3.6 meter telescope. Such a design was developed in response to the increasing demand in the astronomical community for a fast and efficient Near IR survey facility taking profit of the small pitch 1k2 and 2k2 Hybrid Focal Plane Arrays recently made available. The prime focus is a privileged location for high throughput instrument since it allows to design imagers with a relatively small amount of optical elements . At the prime focus however the plate scale is constrained to a narrow range of possibility by the F/number of primary mirror since the need to correct for aberrations does not leave much freedom for focal elongation. The ESO 3.6 telescope has a F/3 primary mirror. Unlike most of the new technology telescope of the same size, e.g. NTT or TNG, that have F/2.2 primaries, the longer focal length of the ESO 3.6 allows to reach plate scales of the order of about 15.2 as/mm, matching the scientific requirement for wide field NIR surveys. The Camera consist in a prime focus corrector made of 4 spherical lenses in fused silica providing a corrected field of 45 arcmin 0. The limited number of optical elements maximizes the throughput but does not allow to re-image the telescope pupil to position a cold stop. Therefore a detailed mode of the telescope thermal background has been sued to optimized the baffling system. Only a non-contiguous fraction of the corrected field is covered by 4 Rockwell HAWAII II 2k2 HgCdTe chips.
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Filippo Maria Zerbi, Fabio Bortoletto, Paolo Conconi, Daniele Gardiol, Emilio Molinari, Claudio Pernechele, Dario Rizzoli, "Conceptual design for a NIR prime focus camera for the ESO 3.6", Proc. SPIE 4008, Optical and IR Telescope Instrumentation and Detectors, (16 August 2000); doi: 10.1117/12.395542; https://doi.org/10.1117/12.395542

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