BNL Demonstrates Test Camera

In early February, a team working on the LSST Camera project at Brookhaven National Laboratory (BNL) demonstrated the first successful operation of a test camera using a “vertical slice” of the final camera sensors and electronics. The test assembly contained prototype CCDs and one 48-channel raft electronic board, all housed in a developmental model of the Commissioning Camera cryostat. The raft sensor assembly was set at -100C, and the electronics sink was set at -10C. Using a variety of optical and electronic stimuli, the team found all 48 channels reading out and meeting critical performance specifications for noise, crosstalk and linearity.

Unlike most astronomical imagers, LSST’s mosaic camera will be constructed from 21 identical modules, known as “rafts.” A raft module can be operated as an autonomous, fully functional, and testable camera. The science raft tower (SRT) is the modular building block of the camera focal plane. Each science raft contains a 3 x 3 array of science sensors (CCDs) and the necessary front end and back end electronics. All components of the SRT are contained within the camera cryostat vacuum space.

The vertical slice test involved contributions from many collaborating institutions, notably LPNHE (Paris), University of Pennsylvania, and SLAC.