The Design of the LSST Camera
Abstract
The LSST camera contains a 3.2-gigapixel focal plane array comprised of 189 4Kx4K CCD sensors with 10 micron pixels. The focal plane images 10 square degrees on the sky per exposure creating a data flow of about 18TBs of data per night. The sensors are deep depletion, back-illuminated devices with a highly segmented architecture that enables the entire array to be read out in 2s. The detectors are grouped into 3 x 3 arrays called rafts All the rafts are identical; each contains its own dedicated front-end and back-end electronics boards, which fit within the footprint of its sensors, thus serving as a 144-megapixel camera on its own. The rafts and associated electronics are mounted on a silicon carbide grid inside a vacuum. The grid also contains four sets of guide sensors and wavefront sensors at the edge of the field. The entrance window to the cryostat is the third of three refractive lenses. The other two lenses are mounted in the front of the camera body with the largest lens approximately 1.5 meters in diameter. The camera body, 1.6 meters by 3 meters, also contains a mechanical shutter and a filter exchange system holding five large optical filters, any of which can be inserted into the camera field of view for a given exposure. A sixth optical filter will also be fabricated and can replace any of the five filters that is accomplished during daylight hours. The entire camera assembly weighs approximately 3,000 kilograms. The individual sub-systems of the LSST camera that has led to the reference design are shown.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AAS...21113719G