Assembly of the Dark Energy Survey CCD Imager

The Dark Energy Camera (DECam) is the new wide field prime-focus imager for the Blanco 4m telescope at CTIO. This instrument is a 2.2 sq. deg. camera with a 45 cm diameter focal plane consisting of 62 2k × 4k CCDs and 12 2k × 2k CCDs and was developed for the Dark Energy Survey that will start operations at CTIO in 2011. DECam includes the vessel shell, the optical window cell, the CCDs with their readout electronics and vacuum interface, the focal plane support plate and its mounts, and the cooling system and thermal controls. Assembly of the imager, alignment of the focal plane and installation of the CCDs are described. During DECam development a full scale prototype was used for multi-CCD readout tests. This test vessel went through several stages as the CCDs and related hardware progressed from early prototypes to final production designs.