The CCD imaging systems for DEIMOS

The DEep Imaging Multi-Object Spectrograph (DEIMOS) images with an 8K x 8K science mosaic composed of eight 2K x 4K MIT/Lincoln Lab (MIT/LL) CCDs. It also incorporates two 1200 x 600 Orbit Semiconductor CCDs for active, close-loop flexure compensation. The science mosaic CCD controller system reads out all eight science CCDs in 40 seconds while maintaining the low noise floor of the MIT/Lincoln Lab CCDs. The flexure compensation (FC) CCD controller reads out the FC CCDs several times per minute during science mosaic exposures. The science mosaic CCD controller and the FC CCD controller are located on the electronics ring of DEIMOS. Both the MIT/Lincoln Lab CCDs and the Orbit flexure compensation CCDs and their associated cabling and printed circuit boards are housed together in the same detector vessel that is approximately 10 feet away from the electronics ring. Each CCD controller has a modular hardware design and is based on the San Diego State University (SDSU) Generation 2 (SDSU-2) CCD controller. Provisions have been made to the SDSU-2 video board to accommodate external CCD preamplifiers that are located at the detector vessel. Additional circuitry has been incorporated in the CCD controllers to allow the readback of all clocks and bias voltages for up to eight CCDs, to allow up to 10 temperature monitor and control points of the mosaic, and to allow full-time monitoring of power supplies and proper power supply sequencing. Software control features of the CCD controllers are: software selection between multiple mosaic readout modes, readout speeds, selectable gains, ramped parallel clocks to eliminate spurious charge on the CCDs, constant temperature monitoring and control of each CCD within the mosaic, proper sequencing of the bias voltages of the CCD output MOSFETs, and anti-blooming operation of the science mosaic. We cover both the hardware and software highlights of both of these CCD controller systems as well as their respective performance.