STEPS TOWARD EFFICIENT MOSAIC CCD SYSTEM-DESIGN

The areas of available optical detectors are too small for large imagi ng formats, such as telescope focal planes. One way to obtain large de tector areas is to assemble mosaics of CCDs. Parallel driving of many CCDs rules out the possibility of individual tuning; however, such opt imization is important, when the ultimate low light-level performance is required, particularly for new, or mixed, devices. In this work, an entirely novel approach, where the drive waveforms are multiplexed an d interleaved, is described. This method reduces the number of leadout connections and permits individual device optimization. The controlle r basically comprises one memory device plus one PLD (programmable log ic device) where most of the logic is integrated, minimizing the chip count and improving the efficiency of the system greatly. The system s oftware has a flexible architecture for tailoring to specific operatio n modes and readout modes. The controller design can handle a mixture of CCD types in any geometric format. The laboratory prototype has bee n integrated and demonstrated.