The Linear Coherent Light Source (LCLS), a free electron laser operating from 250eV to10keV at 120Hz, is opening windows on new science in biology, chemistry, and solid state, atomic, and plasma physics<sup>1,2</sup>. The FEL provides coherent x-rays in femtosecond pulses of unprecedented intensity. This allows the study of materials on up to 3 orders of magnitude shorter time scales than previously possible. Many experiments at the LCLS require a detector that can image scattered x-rays on a per-shot basis with high efficiency and excellent spatial resolution over a large solid angle and both good S/N (for single-photon counting) and large dynamic range (required for the new coherent x-ray diffractive imaging technique<sup>3</sup>). The Cornell-SLAC Pixel Array Detector (CSPAD) has been developed to meet these requirements. SLAC has built, characterized, and installed three full camera systems at the CXI and XPP hutches at LCLS. This paper describes the camera system and its characterization and performance.
The Large Synoptic Survey Telescope (LSST) is a large aperture, wide-field facility designed to provide deep images of
half the sky every few nights. There is only a single instrument on the telescope, a 9.6 square degree visible-band
camera, which is mounted close to the secondary mirror, and points down toward the tertiary. The requirements of the
LSST camera present substantial technical design challenges. To cover the entire 0.35 to 1 μm visible band, the camera
incorporates an array of 189 over-depleted bulk silicon CCDs with 10 μm pixels. The CCDs are assembled into 3 x 3
"rafts", which are then mounted to a silicon carbide grid to achieve a total focal plane flatness of 15 μm p-v. The CCDs
have 16 amplifiers per chip, enabling the entire 3.2 Gigapixel image to be read out in 2 seconds. Unlike previous
astronomical cameras, a vast majority of the focal plane electronics are housed in the cryostat, which uses a mixed
refrigerant Joule-Thompson system to maintain a -100ºC sensor temperature. The shutter mechanism uses a 3 blade
stack design and a hall-effect sensor to achieve high resolution and uniformity. There are 5 filters stored in a carousel
around the cryostat and the auto changer requires a dual guide system to control its position due to severe space
constraints. This paper presents an overview of the current state of the camera design and development plan.
The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, modified Paul-Baker design,
with an 8.4-meter primary mirror, a 3.4-m secondary, and a 5.0-m tertiary feeding a refractive camera design with 3
lenses (0.69-1.55m) and a set of broadband filters/corrector lenses. Performance is excellent over a 9.6 square
degree field and ultraviolet to near infrared wavelengths.
We describe the image quality error budget analysis methodology which includes effects from optical and
optomechanical considerations such as index inhomogeneity, fabrication and null-testing error, temperature
gradients, gravity, pressure, stress, birefringence, and vibration.
The Large Synoptic Survey Telescope (LSST) project has evolved from just a few staff members in 2003 to about 100 in
2010; the affiliation of four founding institutions has grown to 32 universities, government laboratories, and industry.
The public private collaboration aims to complete the estimated $450 M observatory in the 2017 timeframe. During the
design phase of the project from 2003 to the present the management structure has been remarkably stable. At the same
time, the funding levels, staffing levels and scientific community participation have grown dramatically. The LSSTC
has introduced project controls and tools required to manage the LSST's complex funding model, technical structure and
distributed work force. Project controls have been configured to comply with the requirements of federal funding
agencies. Some of these tools for risk management, configuration control and resource-loaded schedule have been
effective and others have not. Technical tasks associated with building the LSST are distributed into three subsystems:
Telescope & Site, Camera, and Data Management. Each sub-system has its own experienced Project Manager and
System Scientist. Delegation of authority is enabling and effective; it encourages a strong sense of ownership within the
project. At the project level, subsystem management follows the principle that there is one Board of Directors, Director,
and Project Manager who have overall authority.