Camera Overview

LSST Camera Internal Reviewwith Roger Smith, Cal Tech

Kirk GilmoreOctober 14, 2008

July 7, 2008 SLAC Annual Program Review NSFJune 11, 2008

2

FY-09 FY-10 FY-11 FY-12 FY-13 FY-14 FY-15 FY-16

The current LSST timeline

FY-17FY-07 FY-08

NSF D&D FundingMREFC Proposal Submission

NSF CoDRMREFC Readiness

NSF PDR

NSBNSF CDR NSF MREFC Funding

Commissioning

Operations

DOE R&D Funding

DOE CD-0DOE CD-1

Telescope First Light

DOE OperatingFunds

Camera Ready to Install

NSF + Privately Supported Construction (8.5 years) System First Light

ORR

DOE MIE Funding

Camera Delivered to ChileSensor Procurement Starts

DOE CD-3

DOE CD-2

DOE + Privately Supported Fabrication (5 years) DOE CD-4

Privately Supported camera R&D

Camera Lead Scientist

Kahn (SLAC)

SystemsEngineeringGilmore (act.)

(SLAC)WBS 3.2

Project ControlPrice

(SLAC)WBS 3.1

ElectronicsOliver

(Harvard)WBS 3.5.8

Sensor/RaftDevelopment

Radeka/O’Connor(BNL)

WBS 3.5.4

OpticsOlivier (LLNL)

WBS 3.5.5

CryostatAssemblySchindler(SLAC)

WBS 3.5.7

CalibrationBurke

(SLAC)WBS 3.5.1

Camera Body & Mechanisms

Nordby(SLAC)

WBS 3.5.3

Camera Data Acq. & Control

Schalk(UCSC)

WBS 3.5.6

Camera Integration & Test Planning

Nordby(SLAC)

WBS 3.6

Performance, Safety and Environmental Assurance

(SLAC)WBS 3.3 / 3.4

Observatory Integ., Test & Commission Support

(SLAC)WBS 3.7

Corner RaftWFS/Guider

Olivier(LLNL)

WBS 3.5.9

Camera UtilitiesNordby (SLAC)

WBS 3.5.2

Sensor,Elect, Mech. Dev.

Antilogus(IN2P3)

LPNHE LAL APC

Camera Organizational

Chart Camera Project Scientist

Gilmore (SLAC)

Camera Project Manager

Fouts (SLAC)

WBS 3.1

LSST Camera Deliverable Org Chart

ElectronicsOliver

(Harvard)WBS 3.5.8

Sensor/RaftDevelopment

Radeka/O’Connor(BNL)

WBS 3.5.4

OpticsOlivier (LLNL)

WBS 3.5.5

CryostatAssemblySchindler

(SLAC)WBS 3.5.7

CalibrationBurke(SLAC)

WBS 3.5.1

Camera Body Mechanisms

Nordby(SLAC)

WBS 3.5.3

Data Acq. & ControlSchalk(UCSC)

WBS 3.5.6

Corner RaftWFS/Guider

Olivier(LLNL)

WBS 3.5.9

UtilitiesNordby (SLAC)

WBS 3.5.2

Sensors/FiltersPain/Antilogus

(IN2P3)LPNHE, LAL,APC, LPSC,

LMA

SLAC/LSST M&S to outside institutions via Financial Plan Transfer

The LSST Camera Team: 72 People from 16 Institutions

Brandeis University J. Besinger, K. HashemiBrookhaven 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 WahlHarvard University

N. Felt, J. Geary (CfA), J. Oliver, C. StubbsIN2P3 - 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 StankusOhio State University

K. Honscheid, R. Hughes, B. Winer

Purdue University K. Ardnt, Gino Bolla, J, Peterson, Ian ShipseyRochester Institute of Technology

D. FigerStanford 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

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CNRS - National Center for Scientific ResearchIN2P3 - National Institute for Nuclear Physics and Particle Physics

APC - Lab for Astroparticles and Cosmology (Paris) - Calibration/CCSCC-IN2P3 - Computing Center of IN2P3 (Lyon) - Computing FacilitiesLAL - Lab of Linear Accelerator (Orsay) - ElectronicsLMA - Lab of Advanced Materials (Lyon) - FiltersLPSC - Lab for Subatomic Physics and Cosmology (Grenoble) - CalibrationLPNHE - Lab for Nuclear Physics and High Energy (Paris) - Sensors/Elec.

Four Main Science Themes for LSST

1. Constraining Dark Energy and Dark Matter2. Taking an Inventory of the Solar System3. Exploring the Transient Optical Sky4. Mapping the Milky Way Major Implications to the Camera

• 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

Access port for Manual Changer

L3 Lens Assembly

Filter in on-line position

Camera Housing

Filter Carousel

Camera back flange—interface to telescope

Cryostat support pedestal

Utility Trunk

Filter in stored position

Lens support ring with light baffles

L1 Lens

Auto Changer

L2 Lens with perimeter light absorberAperture ring to define Beam Entrance

SLAC Annual Program Review

9

www.lsst.org

0.6”, 30 m

“good” seeing”star image

Aspheric surface

LSST is a “seeing limited” telescope with ~10 micron (0.2 arc-sec ) diameter images

10 m pixel

Camera:Flat 64 cm CCD array

LSST Optical DesignLSST Optical Design

* f/1.23 * <0.20 arcsec FWHM images in six bands: 0.3 - 1 m * 3.5 ° FOV Etendue = 319 m2deg2

LSST optical layout

Polychromatic diffraction energy collection

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0 80 160 240 320

Detector position ( mm )

Imag

e d

iam

eter

( a

rc-s

ec )

U 80% G 80% R 80% I 80% Z 80% Y 80%

U 50% G 50% R 50% I 50% Z 50% Y 50%

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

3X3 CCD

“RAFT”

4KX4K Science CCD10m pixels

Corner area Wavefront sensingand guiding

LSST focal plane layout

CCD is divided into 16 1Mpix segments with individual readout

32-port CCD32-port CCD

3x3 - 16-port CCDs

Raft tower electronics partitioning

Front End Boards (6 per raft):• 144-channels of video signal chain through CDS processing• clock and bias drive• ASIC-based (ASPIC/SCC)

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

~175K

~235K

Flex cables (~ 500 signals)

Cryo Plate (~170k)

Cold Plate (~230k)

~185K

Molecular Flow Barrier

CCD

PACKAGEDCCD

RAFT

From sensors to rafts to raft/towers -All being prototyped in 08-09

TOWER• 3 x 3 submosaic of CCDs• front end electronics• thermal management components

• Tower is an autonomous, fully-testable 144 Mpixel camera

carrier

CCDconnector

alignmentpins

baseplate

thermal straps

FEE boards

housing (cold mass)

3-pt. mount

cooling planes

Corner raft tower - Prototype in 09 at Purdue

Guider sensor packages

FE double-board unit for Guiders

Vee-block and spring mount system from standard Rafts

WFS sensor package

FE double-board unit for WFS

Focal plane2d

40 mm

Sci CCD

CCD Curvature Sensor

CMOS Guide Sensor

• 17

Thermal control engineering model being developedThermal control engineering model being developed• 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

• Thermal zones: 5 thermal zones in the camera

1. Focal plane array• Cooled by Cryo plate

2. Cryo Plate• Cools Cryo plate, shroud, FEE modules

3. Back end• Cools Cold plate, BEE modules• No temperature stability requirements

4. Camera body• Actively controlled to match ambient temp

5. Utility trunk• Actively controlled to match ambient temp

Zone 5: Utility Trunk

Zone 4: Camera Body

BEEModule

FEEModule

Cryo Plate

Cold Plate

Power, Timing,Comm, Control

Act

uat

ors

Co

ntr

olle

rs

Valve Box

Zone 3: Back End

Utility Room

Chillers Facility A.C.

Facility Water

Gri

d

Gri

d

Zone 1: Focal Plane Array

Zone 2: Cryo Plate

L2

L1

Rafts

Th

erm

Str

ap

Htr

BEEModule

BEEModule

FEEModule

FEEModule

Rafts

Th

erm

Str

ap

Htr

Rafts

Th

erm

Str

ap

Htr

FilterL3

Auto Changer module

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

Requirement Value UnitNumber of filters housed in the Camera at one time 5Max time between two visits in different filters 2 minMinimum operational life of filter changer 40,000 cyclesMinimum operational life of filter carousel 20,000 revMinimum time between preventative maintenance 4,000 cycles

Shutter design being prototyped in 08

* 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

1s close to open time1s open to close time

Housing for Shutter mechanisms

Drive timing belts Motors with 3 drive pulleys of different

diameters

Blades are contoured to fit around convex crown

of L3 to save Z-space

Blades stack beyond field of view when not in use

Guide rail channel tracks cam followers in blades to reduce sagging of blades

Cryostat design overview

Cold Plate

Raft Tower

Cryo Plate

L3 Assembly

Feedthrough Flange

Back flange

Cryostat Housing

Mounting flange

Support Tube

Cryo Line

A camera integration plan is complete

Camera Body

Cryostat

L1/L2 assy

UtilityTrunk

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LSST will build on successes and resources available at SLAC for I&T

GLAST - LAT

Built at SLAC

LSST Camera

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

Mechanical

Contamination

Metrology

# Activity Description of Activity/Risk Mitigation Risk Needing Mitigation

1A Optical Coating EvaluationEvaluate results of vendor studies on optical coatings

Camera optical coatings won't meet specifications

1B Optical Tolerance AnalysisIncorporate FEA structural and thermal analysis into camera optics tolerance analysis

Camera optics structural and thermal environment will prevent camera optics from meeting image quality spec.

1CWavefront Sensing and Guiding Analysis

Validate conceptual analysis through comparison with lab and sky data

Wavefront sensing and guiding won't meet image quality specifications

# Activity Description of Activity/Risk Mitigation Risk Needing Mitigation

1 CCS control system Prototype an instance of the control systemWe need an instance of the controls system to deliver on a test bed

1A graduate student developer @ UI a person to actually write code

# Activity Description of Activity/Risk Mitigation Risk Needing Mitigation

1A CCD characterization test stands

This category includes new Dewar extensions, vacuum equipment, optics, and measurement systems for characterization of CCDs from study contract and prototype contract vendors. The goal for this year is to complete the construction and commissioning of two

Development of overdepleted, multi-output back-illuminated 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

1B Electronics test interfacesPCBs, components, connectors, and cables for interfacing new electronics to CCD sensors.

New front-end electronics modules produced by U. Penn, Harvard, and other LSST groups need vaildation with CCD inputs at -100C temperature.

1C 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

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.

Priority Activity Requesting institution Notes:

All 1Camera Electronics Project Management

Harvard Technical and budgetary project management

Design, Fabricate, and test Raft Control Crate with Version 2.0 BEE board, backplane, Raft Control Module

HarvardGoal is full 144 channel readout electronics for one full raft of LSST science sensors.

Summary of sub-system risk mitigation activities

Optics

CCS

CCD

Electronics