Camera Overview
LSST Camera Internal Review
with Roger Smith, Cal Tech
Kirk Gilmore
October 14, 2008
The current LSST timeline
FY-07
FY-08
FY-09
FY-10
FY-11
FY-12
FY-13
FY-14
FY-15
FY-16
FY-17
NSF D&D Funding
MREFC Proposal Submission
NSF CoDR
MREFC Readiness
NSF PDR
NSB
NSF CDR
NSF MREFC Funding
Telescope First Light
NSF + Privately Supported Construction (8.5 years)
System First Light
Commissioning
ORR
Operations
DOE Operating
Funds
Privately Supported camera R&D
DOE MIE Funding
DOE + Privately Supported Fabrication (5 years)
Sensor Procurement Starts
DOE R&D Funding
July 7, 2008
DOE CD-0
DOE CD-3
DOE CD-2
SLAC Annual Program Review NSF
DOE CD-1
June 11, 2008
DOE CD-4
Camera Delivered to Chile
Camera Ready to Install
2
Camera Lead
Scientist
Kahn (SLAC)
Camera
Organizational
Chart
Camera Project Camera Project
Scientist
Manager
Gilmore (SLAC)
Fouts (SLAC)
WBS 3.1
Project Control
Price
(SLAC)
WBS 3.1
Systems
Engineering
Gilmore (act.)
(SLAC)
WBS 3.2
Performance, Safety and
Environmental Assurance
(SLAC)
WBS 3.3 / 3.4
Electronics
Oliver
(Harvard)
WBS 3.5.8
Optics
Olivier
(LLNL)
WBS 3.5.5
Sensor/Raft
Development
Radeka/O’Connor
(BNL)
WBS 3.5.4
Camera Integration
& Test Planning
Nordby
(SLAC)
WBS 3.6
Camera Body &
Mechanisms
Nordby
(SLAC)
WBS 3.5.3
Cryostat
Assembly
Schindler
(SLAC)
WBS 3.5.7
Observatory Integ., Test
& Commission Support
(SLAC)
WBS 3.7
Calibration
Burke
(SLAC)
WBS 3.5.1
Camera Data
Acq. & Control
Schalk
(UCSC)
WBS 3.5.6
Sensor,Elect,
Mech. Dev.
Antilogus
(IN2P3)
LPNHE LAL APC
Corner Raft
WFS/Guider
Olivier
(LLNL)
WBS 3.5.9
Camera Utilities
Nordby
(SLAC)
WBS 3.5.2
LSST Camera Deliverable Org Chart
SLAC/LSST M&S to outside institutions via Financial Plan Transfer
Electronics
Oliver
(Harvard)
WBS 3.5.8
Optics
Olivier
(LLNL)
WBS 3.5.5
Sensor/Raft
Development
Radeka/O’Connor
(BNL)
WBS 3.5.4
Cryostat
Assembly
Schindler
(SLAC)
WBS 3.5.7
Camera Body
Mechanisms
Nordby
(SLAC)
WBS 3.5.3
Calibration
Burke
(SLAC)
WBS 3.5.1
Data Acq. &
Control
Schalk
(UCSC)
WBS 3.5.6
Utilities
Nordby
(SLAC)
WBS 3.5.2
Corner Raft
WFS/Guider
Olivier
(LLNL)
WBS 3.5.9
Sensors/Filters
Pain/Antilogus
(IN2P3)
LPNHE, LAL,
APC, LPSC,
LMA
The LSST Camera Team: 72 People from
16 Institutions
Brandeis University
J. Besinger, K. Hashemi
Brookhaven National Lab
S. Aronson, C. Buttehorn, J. Frank, J.
Haggerty, I. Kotov, P. Kuczewski, M. May, P.
O’Connor, S. Plate, V. Radeka, P. Takacs
Florida State University
Horst Wahl
Harvard University
N. Felt, J. Geary (CfA), J. Oliver, C. Stubbs
IN2P3 - France
R. Ansari, P. Antilogus, E. Aubourg, S.
Bailey, A. Barrau, J. Bartlett, R. Flaminio, H.
Lebbolo, M. Moniez, R. Pain, R. Sefri, C. de
la Taille, V. Tocut, C. Vescovi
Lawrence Livermore National Lab
S. Asztalos, K. Baker, S. Olivier, D. Phillion,
L. Seppala, W. Wistler
Oak Ridge National Laboratory
C. Britton, Paul Stankus
Ohio State University
K. Honscheid, R. Hughes, B. Winer
Purdue University
K. Ardnt, Gino Bolla, J, Peterson, Ian Shipsey
Rochester Institute of Technology
D. Figer
Stanford Linear Accelerator Center G. Bowden, P. Burchat (Stanford), D. Burke, M.
Foss, K. Fouts, K. Gilmore, G. Guiffre, M. Huffer, S.
Kahn (Stanford), E. Lee, S. Marshall, M. Nordby, M.
Perl, A. Rasmussen, R. Schindler, L. Simms
(Stanford), T. Weber
University of California, Berkeley
J.G. Jernigan
University of California, Davis
P. Gee, A. Tyson
University of California, Santa Cruz
T. Schalk
University of Illinois, Urbana-Champaign
J. Thaler
University of Pennsylvania
M. Newcomer, R. Van Berg
IN2P3 - France R&D support for camera development
QuickTime™ and a
decompressor
are needed to see this picture.
CNRS - National Center for Scientific Research
IN2P3 - National Institute for Nuclear Physics and Particle Physics
APC - Lab for Astroparticles and Cosmology (Paris) - Calibration/CCS
CC-IN2P3 - Computing Center of IN2P3 (Lyon) - Computing Facilities
LAL - Lab of Linear Accelerator (Orsay) - Electronics
LMA - Lab of Advanced Materials (Lyon) - Filters
LPSC - Lab for Subatomic Physics and Cosmology (Grenoble) - Calibration
LPNHE - Lab for Nuclear Physics and High Energy (Paris) - Sensors/Elec.
Four Main Science Themes for LSST
1.
2.
3.
4.
Constraining Dark Energy and Dark Matter
Taking an Inventory of the Solar System
Exploring the Transient Optical Sky
Mapping the Milky Way
Major Implications to the Camera
1.
2.
3.
4.
Large Etendue
Excellent Image Quality and Control of PSF Systematics
High Quantum Efficiency over the Range 330 – 1,070 nm
Fast Readout
The camera consists of the camera
body and cryostat
Camera back flange—interface to telescope
L3 Lens Assembly
Access port for Manual Changer
Filter in on-line position
Utility Trunk
Auto Changer
Cryostat support pedestal
Filter Carousel
Filter in stored position
Camera Housing
L2 Lens with perimeter light absorber
Aperture ring to define Beam
Entrance
Lens support ring with light baffles
L1 Lens
LSST is a “seeing limited” telescope with
~10 micron (0.2 arc-sec ) diameter images
www.lsst.org
Camera:
Flat 64 cm f CCD
array
Aspheric surface
“good” 0.6”,
seeing” 30 mm
star
image
10 mm
pixel
SLAC Annual Program Review
9
LSST Optical Design
Image diameter ( arc-sec )
* f/1.23
* <0.20 arcsec FWHM images in six bands: 0.3 - 1 mm
* 3.5 ° FOV  Etendue = 319 m2deg2
Polychromatic diffraction energy collection
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
80
160
240
320
Detector position ( mm )
U 80%
G 80%
R 80%
I 80%
Z 80%
Y 80%
U 50%
G 50%
R 50%
I 50%
Z 50%
Y 50%
LSST optical layout
Focal plane readout : The challenge
Large focal plane  189 Sensors, 3.2 Gpixels
High speed readout  2 sec goal
Low read noise, sky noise dominated > ~ 5 e rms
High crosstalk immunity ~ 80 db
Fully synchronous readout across entire focal
plane
* Large number of sensor pads (signals) 
150/sensor ~ 30,000 pads total
* High vacuum environment  contamination
control
* Minimization of vacuum feedthroughs
*
*
*
*
*
Focal plane readout : The strategy
*
*
*
*
*
*
*
*
*
Utilize highly segmented sensors to allow modest read speed
16 segments (ports) / sensor  500 kHz readout
“Raft” based electronics package  9 x 16 = 144 ports per raft
Electronic package located within Dewar to avoid ~30k Dewar
penetrations
FPA electronics packaging requirement All electronics must live
in “shadow” of raft footprint ~ 125 mm x 125 mm
21 rafts 3,024 readout ports (source followers)
Data output on one optical fiber per raft  144 Mpixels/2 sec
~1.4 Gbps on fiber
All raft electronics controlled by single “Timing & Control
Module” for focal plane synchronicity  Timing/Control Port
Timing/Control Port also used for “Engineering Interface” for CCD
studies & setup
LSST focal plane layout
4KX4K
Science CCD
10mm pixels
3X3
CCD
“RAFT”
CCD is divided into 16 1Mpix
segments with individual
readout
Corner area
Wavefront sensing
and guiding
Raft tower electronics partitioning
32-port CCD
32-port CCD
3x3 - 16-port CCDs
~185K
Molecular Flow Barrier
Front End Boards (6 per raft):
• 144-channels of video signal
chain through CDS processing
• clock and bias drive
• ASIC-based (ASPIC/SCC)
~175K
Cryo Plate (~170k)
Flex cables (~ 500 signals)
Cold Plate (~230k)
~235K
BEE motherboard and backplane:
• differential receiver
• signal chain ADC (16+ bits)
• buffers
• data transport to optical fiber
• clock pattern generation
• clock and bias DACs
• temperature monitor / control
From sensors to rafts to raft/towers All being prototyped in 08-09
CCD
thermal straps
FEE boards
PACKAGED
CCD
cooling
planes
connector
CCD
housing
(cold mass)
carrier
alignment
pins
TOWER
• 3 x 3 submosaic of CCDs
• front end electronics
• thermal management components
RAFT
3-pt. mount
baseplate
• Tower is an autonomous,
fully-testable 144 Mpixel
camera
Corner raft tower Prototype in 09 at Purdue
Guider sensor packages
WFS sensor package
CCD Curvature Sensor
Vee-block and spring
mount system from
standard Rafts
2d
Focal plane
Sci CCD
40 mm
CMOS Guide Sensor
FE double-board
unit for WFS
FE double-board
unit for Guiders
Thermal control engineering model being developed
Utility Room
Chillers
BEE
Module
1. Focal plane array
Cooled by Cryo plate
Actively controlled to match ambient temp
Therm Strap
FEE
Module
Htr
Therm Strap
Htr
Actively controlled to match ambient temp
FEE
Module
Htr
Cools Cold plate, BEE modules
No temperature stability requirements
5. Utility trunk
•
FEE
Module
Therm Strap
Cools Cryo plate, shroud, FEE modules
Grid
Cryo Plate
4. Camera body
•
BEE
Module
Zone 2: Cryo Plate
3. Back end
•
•
BEE
Module
Cold Plate
2. Cryo Plate
•
Valve Box
Zone 3: Back End
Thermal zones: 5 thermal zones in the camera
•
Facility Water
Facility A.C.
Zone 5: Utility Trunk
Power, Timing,
Comm, Control
Grid
•
Design approach
– Create isolated zones for controlling the
camera environments
– Control zones independently to produce the
environments needed
– Allow for on-telescope cool-down/warm-up
Actuators
Controllers
•
Rafts
Rafts
Rafts
Zone 1: Focal Plane Array
L3
Filter
L2
Zone 4: Camera Body
L1
•
17
Filter exchange mechanism in
prototyping
Filter exchange time = 120s
Filter exchange consists of 3 assemblies
– Carousel
• Stores up to five filters out of the field of
view
• Moves chosen filter into exchange position
– Auto Changer
• Supports filter in the field of view
• Moves filter from storage position into field
of view
– Manual Changer
• Used for filter exchange from outside the
camera
Auto Changer
module
Requirement
Number of filters housed in the Camera at one time
Max time between two visits in different filters
Minimum operational life of filter changer
Minimum operational life of filter carousel
Minimum time between preventative maintenance
Value Unit
5
2
min
40,000 cycles
20,000 rev
4,000 cycles
Shutter design being prototyped in 08
Drive timing belts
Motors with 3 drive
pulleys of different
diameters
* Shutter is comprised of two
stacks of 3 blades each
– One stack retracts to start
an exposure, and the
second stack extends to
stop it
This ensures uniform
exposure time for all
pixels
Blades stack beyond
field of view when not in use
Guide rail channel tracks cam
followers in blades to reduce
sagging of blades
Housing for Shutter
mechanisms
1s close to open time
1s open to close time
Blades are contoured to
fit around convex crown
of L3 to save Z-space
Cryostat design
overview
Feedthrough Flange
Back flange
Cold Plate
Cryostat Housing
L3 Assembly
Cryo Line
Mounting flange
Support Tube
Cryo Plate
Raft Tower
A camera integration plan is complete
Cryostat
Utility
Trunk
Camera Body
L1/L2 assy
LSST will build on successes and resources available
at SLAC for I&T
GLAST - LAT
LSST
Camera
Built at SLAC
QuickTime™ and a
decompressor
are needed to see this picture.
Camera risk mitigation plan prior to construction
R&D Effort
Plan
Status
Demonstrate sensor
performance
Establish all specs are
met:
Flatness, high fill factor,
electrical parameters,
Study phase sensors
received and being
evaluated
Efficient sensor
procurement
Establish cost, yield and
performance of sensors
PO’s being drafted that
address risk areas.
Prototype phase starting
Establish reliability of
shutter/filter excahnge
mechanism
Build prototype and test
Design completed.
Procurement of parts
begun
Evaluate outgassing
properties of cryostat
components
Contamination control
demonstrated in
engineering cryostat
Contamination testing
started. Materials
selection process begun.
75cm filter w/multilayer
coatings produced with
non-uniformity of <1% .
Fabrication of samples in
large coating chamber to
evaluate uniformity of filter
transmission
Passbands defined. Total
system throughput
modeled. Some witness
samples already
produced. RFP to
potential vendors under
review.
Summary of sub-system risk mitigation activities
#
Activity
1A
Kinematic coupling prototype
1B
Grid thermal-mech analysis
Mechanical
#
Activity
Description of Activity/Risk Mitigation
Prototype kinematic coupling design concept;
evaluate material/coating options; test over full temp
range
Develop Grid/Cryo Plate thermal and structural
model (steady-state)
Description of Activity/Risk Mitigation
Risk Needing Mitigation
Kinematic coupling is not suitably stable and
repeatable to keep CCD's in flatness spec
Grid thermal-mech motion could move CCD's
beyond their allowable position envelope
Risk Needing Mitigation
1A
Contamination Study Chamber
Construction
Complete Construction and Commissioning of
Contamination Study Chamber and Move to
Campus Lab
Materials in Cryostat will outgas and degrade the
performance of the CCD's. All potential materials
in cryostat will need to be examined.
1B
Contamination Testing
Purchase material samples and commercial
coatings. Student labor (10hrs/weekx26wks)
Demonstrate that the most serious potential
contaminents can be controlled without changing
design of the cryostat
Contamination
#
Activity
1
Raft Kinematic Coupling
Prototype (testing)
Metrology
Raft Kinematic Coupling Testing
2
follow-up & Specification
Description of Activity/Risk Mitigation
Fit-up of metrology facility for testing;
Evaluate results of testing and repeat tests (using
other materials and surface finishes indicative of
superior performance) as necessary. Contingent on
testing results described above.
Risk Needing Mitigation
Budget environmental, surface & materials
related effects to K.C. Mechanical properties, or
wear-in. Testing required to isolate individual
effects.
Nominal kinematic coupling
materials/finish/coating choices may not provide
required stability and reproducibility.
Summary of sub-system risk mitigation activities
#
Optics
Optical Coating Evaluation
1B
Optical Tolerance Analysis
Incorporate FEA structural and thermal analysis into
camera optics tolerance analysis
1C
Wavefront Sensing and Guiding
Analysis
Validate conceptual analysis through comparison
with lab and sky data
1
Activity
CCS control system
1A
#
1A
CCD
1B
1C
Priority
All 1
Electronics
Description of Activity/Risk Mitigation
Evaluate results of vendor studies on optical
coatings
1A
#
CCS
Activity
Description of Activity/Risk Mitigation
Prototype an instance of the control system
graduate student developer @ UI
Activity
Description of Activity/Risk Mitigation
This category includes new Dewar extensions,
vacuum equipment, optics, and measurement
systems for characterization of CCDs from study
CCD characterization test stands
contract and prototype contract vendors. The goal
for this year is to complete the construction and
commissioning of two
Electronics test interfaces
PCBs, components, connectors, and cables for
interfacing new electronics to CCD sensors.
Raft prototypes
This category includes design and fabrication of
silicon carbide raft prototype(s), fixturing, and
measurement equipment for studying dimensional
stability of rafts and sensor-raft assemblies. We plan
the first demonstration of focal plane mosaic flatnes
Activity
Camera Electronics Project
Management
Design, Fabricate, and test Raft
Control Crate with Version 2.0
BEE board, backplane, Raft
Control Module
Requesting institution
Risk Needing Mitigation
Camera optical coatings won't meet
specifications
Camera optics structural and thermal
environment will prevent camera optics from
meeting image quality spec.
Wavefront sensing and guiding won't meet
image quality specifications
Risk Needing Mitigation
We need an instance of the controls system to
deliver on a test bed
a person to actually write code
Risk Needing Mitigation
Development of overdepleted, multi-output backilluminated CCDs is the number one technical
and schedule risk to the LSST camera. Maturity
of prototype sensors needs to be determined by
testing at BNL. A facility for conducting tests in a
reproducible man
New front-end electronics modules produced by
U. Penn, Harvard, and other LSST groups need
vaildation with CCD inputs at -100C
temperature.
Assembly procedure to ensure 6.5micron
coplanarity of sensors on rafts requires
experimental study. Failure to achieve required
flatness would severely compromise image
quality of the camera.
Notes:
Harvard
Technical and budgetary project management
Harvard
Goal is full 144 channel readout electronics for
one full raft of LSST science sensors.