7 March 2003 The CFHT MegaCam 40 CCDs camera: cryogenic design and CCD integration
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Abstract
MegaCam is an imaging camera with a 1 square degree field of view for the new prime focus of the 3.6 meter Canada-France-Hawaii Telescope. In building the MegaCam mosaic we encountered unprecedented challenges from both the large size of each CCD device (2K x 4.5K with 13.5 micron square pixels each) and the large size of the mosaic in which 40 devices have been assembled in a nearly 4-buttable edge manner on a cold plate. The CCD mosaic flatness of ± 16 μm has been optically checked at its nominal functioning temperature. The CCD mosaic is cooled at 153 K with a cryogenic unit; a close cycle pulsed tube with a power of 90 W at 140 K. A cold capacity, allows a slow warm-up during cooling shutdowns and a thermal dispatching leads to a temperature uniformity better than 3 K on the whole mosaic. The camera cryostat is designed in order to have easy access to the CCDs. The vacuum needed to avoid CCD contamination, leaded us to the use of low out-gassing materials in the cryostat. The instrument was delivered to the observatory on June 10, 2002 and first light is scheduled in October 2002.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stephan Aune, Olivier Boulade, Xavier Charlot, P. Abbon, Pierre Borgeaud, Pierre-Henri Carton, M. Carty, J. Da Costa, D. Desforge, H. Deschamps, Dominique Eppelle, Pascal Gallais, L. Gosset, Remy Granelli, Michel Gros, Jean de Kat, Denis Loiseau, J. L. Ritou, Jean Yves Rousse, Pierre Starzynski, Nicolas Vignal, and Laurent G. Vigroux "The CFHT MegaCam 40 CCDs camera: cryogenic design and CCD integration", Proc. SPIE 4841, Instrument Design and Performance for Optical/Infrared Ground-based Telescopes, (7 March 2003); doi: 10.1117/12.460340; https://doi.org/10.1117/12.460340
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