The Large Synoptic Survey Telescope (LSST) focal plane consists of 21 autonomous modules [raft tower modules (RTMs)], each of which contains nine thick, fully depleted 4k × 4k CCDs with associated control and readout electronics. To enable LSST’s repetitive short-exposure cadence while maintaining high duty factor and low read noise, the readout is highly parallelized into 3024 independent video channels (16 per CCD and 144 per RTM). Two vendors supplied the LSST sensors; the devices have compatible mechanical and electrical interfaces and meet the same electro-optic specifications, but each RTM is constructed with sensors from a single supplier. The full complement of rafts was assembled at Brookhaven National Laboratory during January 2017 to January 2019. Each unit underwent extensive electro-optic and metrology characterization at operating temperature, the results of which are presented here along with a discussion of uniformity and stability.
Prototype sensors and preproduction CCDs were delivered by vendors and they have been used for developing test procedures and protocols. Building upon this experience, two test stands were designed and commissioned at Brookhaven National Laboratory for production electro-optical testing.
In this article, the sensor acceptance criteria are outlined and discussed, the test stand design and used equipment are presented and the results from commissioning sensor runs are shown.
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