The Integration and Verification Testing of the Large Synoptic Survey Telescope (LSST) Camera is described. The LSST Camera will be the largest astronomical camera ever constructed, featuring a 3.2 giga-pixel focal plane mosaic of 189 CCDs with in-vacuum controllers and readout, dedicated guider and wavefront CCDs, a three element corrector with a 1.6-meter diameter initial optic, six optical filters covering wavelengths from 320 to 1000 nm with a novel filter exchange mechanism, and camera-control and data acquisition capable of digitizing each image in two seconds. In this paper, we describe the integration processes under way to assemble the Camera and the associated verification testing program. The Camera assembly proceeds along two parallel paths: one for the focal plane and cryostat and the other for the Camera structure itself. A range of verification tests will be performed interspersed with assembly to verify design requirements with a test-as-you-build methodology. Ultimately, the cryostat will be installed into the Camera structure as the two assembly paths merge, and a suite of final Camera system tests performed. The LSST Camera is scheduled for completion and delivery to the LSST observatory in 2020.
An electronic traveler system has been implemented for the LSST Camera. Its purpose is to guide execution of procedures on the hardware and associate any resulting test data, analysis results and configurations with the tested devices. The system is accessible from a web browser or via a REST API and uses a MySQL database to provide a history of the assembly hierarchy, hardware locations and test procedure instances, along with locations of the resulting test data. Components of the system are entirely experiment-independent with the exception of the Data Portal web application, which provides expert knowledge by querying the eTraveler database.
The LSST Camera focal plane comprises twenty-one raft tower modules (RTMs), each with nine CCD sensors and their associated electronics. RTMs are assembled at Brookhaven National Lab and shipped to SLAC National Lab, where they must be re-verified before being assembled into the full focal plane. The process for accepting an RTM at SLAC has been thoroughly documented, including unpacking a raft from its shipping container, verifying aliveness of the electrical connections, performing metrology and electro-optical testing in an environment similar to the full Camera, and finally storing the RTM until it can be installed into the LSST Camera