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					   NGAO System Design Phase
           Update


Peter Wizinowich, Rich Dekany, Don Gavel, Claire Max
                   for NGAO Team

                      SSC Meeting
                    January 24, 2007
             Presentation Sequence
• SSC Co-Chair Questions
• Management Update
  A.   Management Structure
  B.   Systems Engineering Management Plan
  C.   Documentation & Coordination
  D.   Instruments Working Group
  E.   Project Report #1

• Technical Update
  – Science Requirements
  – Performance Budgets
  – Trade Studies

• Summary
                                             2
              SSC Co-Chair Questions
All of the following questions are addressed in the Systems Engineering
    Management Plan (summarized in the following Management update
    slides):
1. What is the product of this study phase?
   •   Following Keck development process (see System Design phase
       deliverables on slide 6). Includes conceptual design (with options), initial
       cost estimate & management plan for remaining project. Instrument
       concepts developed to proposal level (precursor to their System Design
       phase).
2. Are any intermediate reviews planned?
   •   Frequent internal product reviews, including cost reviews in Aug & Dec.
       SDR at end of this phase (3/31/08). Project reports provided prior to each
       SSC meeting.
3. Who is doing what, and what % of time is each person devoting to
   NGAO?
   •   Details in project plan. High level summary of key personnel on slide 10.
4. What are the major goals/milestones of this phase?
   •   See milestones on slide 9.
                                                                                3
               SSC Co-Chair Questions
5. What are the big issues and how are they being addressed?
    •   Big picture: Cost, schedule & performance + structuring the program to suit the
        funding. Science & engineering team working closely with management to produce
        a compelling & realistic vision.
    •   Near term: Science community input & team ramp-up. Engaging scientists in
        science case requirements & performance budgets. Freeing personnel from other
        responsibilities.
6. What is the timescale for this phase and when can the SSC expect a full
   report?
    •   See schedule on slide 15.
7. What is the relationship between the NGAO team and the AOWG
    –   AOWG – Bouchez, Dekany, Koo, Larkin, Liu (co-chair), Macintosh, Marchis,
        Matthews, Max (co-chair) + Ellis (rotating on)
    –   The AOWG was a very active participant in the NGAO proposal.
    –   Max, Liu & Marchis are leading the science case requirements
    –   AOWG last met 8/06.
8. Comparison of NGAO versus planned AO performance of current generation.
   Why should we believe new models?
    –   Addressed in the performance budgets section.
                                                                                   4
            A. Management Structure
•   Proposal approved at Jun/06 SSC & Board meetings
•   WMKO, UCO & COO Directors subsequently established
    an Executive Committee (EC) to manage System Design
    phase:
      Wizinowich-WMKO (chair), Dekany-Caltech, Gavel-UCSC, Max-
      UCSC, CFAO (project scientist)




                                                              5
    B. Systems Engineering Management Plan
                                (SEMP)
•   SEMP submitted to Directors at end of Sept/06
    –   Verbal approval received to proceed
    –   Budget approval being finalized
•   System design started Oct/06
    –   Completion planned for mid-FY08
•   Products of this study phase (Q1) - System design phase
    deliverables
    –   System Requirements Document - Science & Observatory
        requirements & flow down to system requirements
    –   System Design Manual – Performance budgets, functional
        requirements, system & subsystem architectures
    –   SEMP – For remaining NGAO phases
    –   System Design Report – Summary for System Design Review

                                                                  6
                      B. SEMP: Approach
              Science        Technical      Initial     Performance
            Requirements    Implications   Concept      Assessment



1.   Initial focus on requirements & performance budgets to ensure that we
     understand largest levers on the design
2.   Initial attempt at defining the AO system architecture & the functional
     requirements for the major systems
3.   In parallel with 1 & 2 perform trade studies to better understand the
     appropriate design choices
4.   A process of iteration and refinement will lead to the final version of the
     AO architecture & major systems requirements
     •   Includes continued development of performance budgets & functional
         requirements
5.   Develop cost estimates & plans for remainder of NGAO project


                                                                              7
                                        B. SEMP: Budget
                                                                          Cost ($k)
WBS                                    Name                        FY07    FY08       Total
 1         Management                                               74      49        123
 2         System Requirements                                     119       3        122
 3         System Design                                           560      90        650
 4         Systems Engineering Management Plan                      5       79         84
           Travel/Procurements                                      40      20         60
           Contingency (part of overall Observatory
           contingency)                                             10      94        104
                                                    Total ($k) =   808     335        1143

                        Work (hours)
 Institute      FY07       FY08        Total   $163k increase in cost of labor since
     COO        2836        702        3589    proposal, due to distributed project
  UCSC          2991        845        3926    nature
 WMKO           5355       1852        7360
Students        1850         0         1850    Total work same as in original proposal
 Total =        13032      3399    16725

                                                                                              8
                          MILESTONE                      DATE            DESCRIPTION
                       SD SEMP Approved                 10/9/06       Approval of plan by Directors

                    SD phase contracts in place         10/27/06   Contracts issued to Caltech & UCSC
                                                                       for the system design phase

               Science Requirements Summary v1.0        10/27/06        Initial Release of Science
                                                                      Requirements as input to trade
                                                                    studies & performance budgeting
B. SEMP:       System Requirements Document v1.0        12/8/06    Initial release with emphasis on the

Milestones                                                                  science requirements

               Performance Budgets Summary v1.0         2/27/07    1st round of all performance budgets
                                                                         complete & documented

                  System Requirements Doc v2.0          3/22/07                 2nd release

                     Trade Studies Complete             5/25/07       All trade studies complete &
                                                                   documented (as a series of KAONs)

                  System Requirements Doc v3.0          7/12/07    3rd release of System Requirements

                   System Design Manual v1.0            8/31/07    1st release of System Design Manual

                   Technical Risk Analysis v1.0         11/13/07     1st round of project risk analysis
                                                                          complete & documented

                      Cost Review Complete              11/30/07     Project cost estimates complete,
                                                                    documented & internally reviewed

                    System Design Manual v2.0            1/8/07                 2nd release

             System Design Review Package Distributed    3/4/08     SDR documents sent to reviewers

                      System Design Review              3/31/08               SDR meeting

                  SDR Report & Project Planning         4/14/08      Final SD phase report including
                                                                                              9
                                                                     results of SDR & project plans
                   Presentation at SSC meeting
                         B. SEMP: Team
      Name   Institute    %                  NGAO-relevant Expertise
Bouchez       COO         11                   AO systems & science
Dekany        COO         33                  EC; AO systems & mgmt
Moore         COO         31                        Instruments
Velur         COO         38          Lasers & wavefront sensors (mechanical)
Bauman        UCSC        21                           Optics
Gavel         UCSC        33                  EC; AO systems & mgmt
Max           UCSC        22                  EC Science Team chair
Postdoc       UCSC        46                        AO science
Adkins       WMKO         15                Instruments & Project Mgmt
Chin         WMKO         18                         Electronics
Flicker      WMKO         38                        AO Modeling
Johansson    WMKO         18             AO Control (software & electronics)
Le Mignant   WMKO         15                   AO science operations
Meguro       WMKO         13                        Mechanical
Neyman       WMKO         67                        AO systems
Wizinowich   WMKO         36               EC chair; AO systems & mgmt


                   Represents 84% of the work force.                            10
        C. Documentation & Coordination
•   NGAO Twiki site at http://www.oir.caltech.edu/twiki_oir/bin/view.cgi/Keck/NGAO/WebHome
•   Includes collections for
    –   Team meetings
        •   Agendas & documents posted in advance; action items posted &
            followed up
    –   Executive committee
        •   Planning & tracking documents
        •   EC weekly meeting minutes
    –   Work packages
        •   Table of WBS elements, planning sheets & products
    –   Performance budgets
        •   Meeting summaries & products
    –   Science team


                                                                                             11
         D. Instruments Working Group
• Instruments Working Group (IWG) being formed for NGAO System
  Design Phase
    – Focused on instrumentation related matters
        • Instrument specialist perspective for NGAO
        • Resource for AO system design team on instrumentation issues
    – Organization (6 to 8 members)
        • 3 to 4 funded from current NGAO plan
             – Responsible for most of technical work related to NGAO instrumentation WBS
             – Sean Adkins (IWG chair, overall systems, detectors, electronics & interfaces)
             – Anna Moore (instrument generalist, optical & mechanical)
             – James Larkin/UCLA IR Lab staff members (instrument design, optical &
               mechanical, cryogenics experience)
             – TBD software engineer
        • 3 to 4 TBD volunteers from NGAO science team
             – Primary contacts with science team for instrument related science requirements
        • Regular meetings will be held involving the entire group
• Additional assistance & advice will be sought from the diverse base of
  the collective instrumentation & technical resources at UC & CIT
                                                                                                12
                      E. Project Report #1
•   Directors‟ requested written project reports prior to each
    SSC meeting
•   1st report submitted to Directors on Jan. 19
    http://www.oir.caltech.edu/twiki_oir/bin/view.cgi/Keck/NGAO/SystemDesignPhasePlanning

•   Good progress made on initiating NGAO System Design
    phase & on building up an effective team
•   Emphasis to date, as planned, on understanding the major
    design drivers through a process of iteratively developing
    the science case requirements & the performance budgets
•   Work has begun on a number of trade studies in support of
    the performance budgets & the future design choices


                                                                                    13
                         E. Project Report #1
#          MILESTONE              DATE                DESCRIPTION                           STATUS
1      SD SEMP Approved           10/9/06        Approval of this plan by the       Verbal approval received.
                                                  Directors. SEMP released to             Written approval
                                                     Directors on 9/29/06.                    requested
2   SD phase contracts in place   10/27/06   Contracts issued to Caltech & UCSC       $50k initial contracts
                                                   for the system design phase.           issued on 12/20
3   Science Case Requirements     10/27/06     Initial Release as input to trade    V1.0 to be completed in
        Summary v1.0 Release                           studies & performance                   Jan/07
                                                             budgeting
4     System Requirements         12/8/06         Initial release of System         V1.0 to be completed in
       Document v1.0 Release                     Requirements with emphasis on                 Jan/07
                                                       science requirements
5     Performance Budgets         2/27/07    1st round of all performance budgets        Good progress
       Summary v1.0 Release                           complete & documented

6   System Requirements Doc       3/22/07    2nd release of System Requirements          Not started yet
            v2.0 Release                                     Document

7    Trade Studies Complete       5/25/07     All trade studies complete (Keck           Good progress
                                                     Adaptive Optics Notes)



                                                                                                        14
E. Project Report #1




                       15
                    E. Project Report #1
Budget
•   $772k budgeted for FY07 in 5-year plan
•   $110k spent in 1st quarter
    –   Low due to slower than planned ramp up of personnel
    –   Average of 4.3 FTEs


Summary
•  Good technical progress as you will see in the following slides
•  Team and management processes now largely in place
•  Expect the teams rate of progress to be close to the rate in the plan
   during the 2nd quarter




                                                                           16
Science Case Requirements
  & System Requirements


Max, Ghez, Law, Liu, Lu, Macintosh, Marchis, Steidel
              Neyman, Wizinowich
     Science Requirements Process
• Approach:
   – Start from significant science case development in proposal
   – Analyze limited set of these key science cases in order to
     understand and document the requirements on NGAO +
     Instruments
   – Begin with cases that stress AO design the most in multiple
     directions
   – Progress to include more science cases
   – Iterate 4 times with AO & instrument requirements


• For each case, discuss
   – Science goals, proposed observations, AO performance
     requirements, instrument requirements


                                                                   19
   Science
Requirements &
 Performance
Budget Process




                 20
        Science Case Requirements Document
                 Release 1 Contents

• JWST and ALMA capabilities
• Future AO capabilities of other observatories
• Key science cases and what they stress most:
   – Multiplicity, size, shape of minor planets
       • High contrast, wavefront error, visible light performance
   – Planetary & brown dwarf companions to low mass stars
       • High contrast
   – General relativistic effects in the Galactic Center
       • Astrometry and radial velocity accuracy
   – Assembly and star formation history of high z galaxies
       • Lower backgrounds, multiple deployable IFUs, sky coverage




                                                                     21
                       JWST capabilities
•   Cryogenic 6.5-m space telescope, launch in
    2013
•   Higher faint-source sensitivity than Keck
    NGAO, due to low backgrounds
•   Not diffraction limited below K band
    –   Primary mirror spec
    –   NIRCAM px scale 0.035”, NIRSpec px scale
        0.1”

•   Areas where Keck NGAO would complement
    JWST
    1. Spectroscopy @ spatial resolution better than
       0.1”,  = 0.6 - 2 μm
    2. Imaging @ spatial resolution better than 0.07”,
        = 0.6 - 2 μm
    3. Multi-IFU spectroscopy
                                                         22
                Key science requirements:
         Multiplicity, size, shape of minor planets
• Minor planet formation history and interiors by
  accurate measurements of size, shape,
  companions
• Small, on-axis imaging field ( ≤ 3 arc sec)
• Relative photometry to 5%, astrometry ≤ 5 mas,
  wavefront error ≤ 170 nm, contrast H  5.5 at
  0.5 arc sec
• Instruments:
    – Imaging: visible and near-IR
    – Near IR IFU spectroscopy: 1.5 arc sec field; still
      need to specify spectral resolution
• Observing modes: non-sidereal tracking,
  <10 minute overhead switching between
  targets, consider queue or flexible scheduling
                                                           Asteroid Sylvia
                                                            and moons
                                                                             23
                  Key Science Requirements:
    Planetary & brown dwarf companions to low mass stars

• Faintness of low-mass stars, brown dwarfs,
  and the youngest stars make them
  excellent NGAO targets
• Small imaging field ≤ 5 arc sec
• Relative photometry to 5%, astrometry to
  PSF FWHM/10, contrast H = 13 at 1 arc
  sec
• Instruments:
   – Imaging 0.9 - 2.4 microns
   – Single near IR IFU spectroscopy, still need
     to specify spectral resolution
• Observing modes: coronagraph needed




                                                           24
               Key Science Requirements:
       General relativistic effects in the Galactic Center

• Measure General Relativistic
  prograde precession of stellar
  orbits in Galactic Center
• Requires astrometric precision of
  100 as (now 250 as) and radial
  velocity precision to 10 km/sec
  (now 20 km/sec)
• K band, wavefront error ≤ 170 nm
• Imaging field 10 x 10 arc sec
• Near IR IFU spectra, R ≥ 4000,
  FOV ≥ 1” x 1”, need IR ADC

                                    Need to evaluate optimal
                                    spectral resolution
                                                               25
           Key Science Requirements:
Assembly and star formation history of high z galaxies

• Redshifts 1.5 ≤ z ≤ 2.5: most active
  star formation, form bulges & disks
    – Optical lines such as H are shifted
      into near IR
• Density 2 - 20 / sq arc sec 
  6 to 12 IFUs in field of regard
• J, H, K bands
• IFU fields ~ 1 x 3 arc sec for sky
  subtraction, 50 mas spaxels, R = 3000
  - 4000, EE > 50% within 50 mas for
  optimal tip-tilt stars
• Low backgrounds: AO system
  < 10-20% of (sky + telescope)         Need to evaluate which high-z
                                             science could be done with
                                             higher backgrounds
                                                                          26
    Science requirements summary to date

• Wavefront error 170 nm or better
   – Need sensitivity study to see how science would fare if wavefront
     error were 200 nm
• Relative photometry to 5%
• Contrast H  5.5 at 0.5 arc sec, H  13 at 1 arc sec
• Astrometry: companions to 5 mas, Galactic Center to
  100 as. Need near-IR ADC.
• K-band backgrounds: AO system + IFU < 10-20% of
  (sky + telescope)
   – Need sensitivity study to see how high-z science would fare at
     higher background levels
• Not yet found a compelling science case for a large
  contiguous field (i.e., MCAO)
                                                                      27
Instruments & observing mode requirements,
                  to date
• Instruments:
   – Refining the requirements developed for the proposal
   – On-axis near-IR imager, field ~ 10 x 10 arc sec, coronagraph
   – On-axis visible imager (to 0.6 or 0.7 m), field ~ 3 x 3 arc sec,
     coronagraph?
   – Near IR deployable IFU:
       •   6 - 12 channels, field of regard TBD
       •   Field of view ~ 1 x 3 arc sec
       •   50 mas spaxels, EE > 50% within 50 mas for optimal tip-tilt stars
       •   Still need to evaluate optimum spectral resolution
• Observing modes:
   – Non-sidereal tracking, <10 minute overhead switching between
     targets, consider queue or flexible scheduling

                                                                               28
NGAO Performance Budget Development



    Dekany, Ghez, Marchis, Max, Liu, Gavel, Flicker, Wizinowich,
     Cameron, Lu, Britton, Macintosh, Neyman, Ireland, Olsen,
       Bouchez, Law, Bauman, Le Mignant, Johansson, Chin
Developing Science-based Performance Budgets

• Systems engineering will consider all of the following
  budgets
   –   Model assumptions
   –   Model/tool validation
   –   Wavefront error vs. sky coverage            for 5-7 science cases
   –   Photometric precision       in crowded and sparse stellar fields
   –   Astrometric accuracy              at the GC and in sparse fields
   –   High-contrast for diffuse debris disks and compact companions
   –   Polarimetric precision            for high-contrast observations
   –   Transmission/background/SNR            for several science cases
   –   Observing efficiency
   –   Observing uptime


                                                                           30
     Performance Budget Development Goals

• Produce a technical report
   – Describing the major drivers, including experimentally supportive
     information, quantitative background, and potential simulation
     results
• Produce a numerical engineering tool to support future
  design iterations
   – Emphasizing abstracted quantitative scaling laws and
     interdependencies
• Support science requirements development
   – Capturing the experience of the science team and reflecting
     quantitative underpinning to current limitations




                                                                    31
     Wavefront Error and Encircled Energy
• Science Cases
    – Maintain all cases from the June „06 NGAO proposal




• Key Drivers for initial budget
    – Uncertainty in tomographic reconstruction error
    – Uncertainty in sodium laser photoreturn from the mesosphere
         • Per delivered Watt, as a function of different pulse formats
         • Requires 50W class lasers to investigate non-linear optical pumping effects
    – Uncertainty in multi-NGS tilt tomography efficacy
         • Not included in original budget development
    – Uncertainty in tip/tilt control efficacy with large tip/tilt mirrors


                                                                                     32
                    Wavefront error budgets
                              Keck Wavefront Error Budget Summary                                                                                                                              Band (microns)
                                                                                                                                                                                   V    R     I   J    H    K
                                                                                                                                                                           m 0.55 0.70 0.91 1.25 1.65 2.20
                                                                                                                                                                          m 16% 31% 17% 30% 24% 22%
                                                                                                                                                                        /D (mas) 11.3 14.4 18.8 25.8 34.0 45.4



• For observations of
                                                                                                                   Wavefront
                              High-order Errors (LGS Mode)                                                                                            Parameter                                  Strehl Ratios
                                                                                                                   Error (rms)

                                Atmospheric Fitting Error                                                                   55   nm                    44   Subaps                   0.67     0.78   0.87     0.93    0.96   0.98

   –   TNO multiplicity         Bandw idth Error
                                High-order Measurement Error
                                LGS Tomography Error
                                Asterism Deformation Error
                                                                                                                            50
                                                                                                                            58
                                                                                                                            60
                                                                                                                            22
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                                       74
                                                                                                                                                     150

                                                                                                                                                    0.50
                                                                                                                                                        5
                                                                                                                                                            Hz
                                                                                                                                                            W
                                                                                                                                                            beacon(s)
                                                                                                                                                            m LLT
                                                                                                                                                                                     0.72
                                                                                                                                                                                     0.64
                                                                                                                                                                                     0.62
                                                                                                                                                                                     0.94
                                                                                                                                                                                              0.81
                                                                                                                                                                                              0.76
                                                                                                                                                                                              0.75
                                                                                                                                                                                              0.96
                                                                                                                                                                                                     0.89
                                                                                                                                                                                                     0.85
                                                                                                                                                                                                     0.84
                                                                                                                                                                                                     0.98
                                                                                                                                                                                                              0.94
                                                                                                                                                                                                              0.92
                                                                                                                                                                                                              0.91
                                                                                                                                                                                                              0.99
                                                                                                                                                                                                                      0.96
                                                                                                                                                                                                                      0.95
                                                                                                                                                                                                                      0.95
                                                                                                                                                                                                                      0.99
                                                                                                                                                                                                                             0.98
                                                                                                                                                                                                                             0.97
                                                                                                                                                                                                                             0.97
                                                                                                                                                                                                                             1.00


   –   Galactic Center
                                Multispectral Error                                                                         25   nm                    30   zenith angle, H band     1.00     1.00   1.00     1.00    1.00   1.00
                                Scintillation Error                                                                         15   nm                 0.37    Scint index, H-band      0.97     0.98   0.99     0.99    1.00   1.00
                                WFS Scintillation Error                                                                     10   nm                 Alloc                            0.99     0.99   1.00     1.00    1.00   1.00
                                                                                             118 nm


   –
                                Uncorrectable Static Telescope Aberrations                                                  43   nm                  64     Acts                     0.79     0.86   0.92     0.95    0.97   0.99
       Field galaxies           Uncorrectable Dynamic Telescope Aberrations
                                Static WFS Zero-point Calibration Error
                                Dynamic WFS Zero-point Calibration Error
                                                                                                                            15
                                                                                                                            20
                                                                                                                            10
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                          Dekens Ph.D
                                                                                                                                                  Alloc
                                                                                                                                                  Alloc
                                                                                                                                                                                     0.97
                                                                                                                                                                                     0.95
                                                                                                                                                                                     0.99
                                                                                                                                                                                              0.98
                                                                                                                                                                                              0.97
                                                                                                                                                                                              0.99
                                                                                                                                                                                                     0.99
                                                                                                                                                                                                     0.98
                                                                                                                                                                                                     1.00
                                                                                                                                                                                                              0.99
                                                                                                                                                                                                              0.99
                                                                                                                                                                                                              1.00
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                      0.99
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                             1.00
                                                                                                                                                                                                                             1.00
                                                                                                                                                                                                                             1.00


   –
                                Go-to Control Errors                                                                         0   nm               Alloc                              1.00     1.00   1.00     1.00    1.00   1.00

       Io                       Residual Na Layer Focus Change
                                DM Finite Stroke Error
                                DM Hysteresis
                                                                                                                             1
                                                                                                                            16
                                                                                                                            13
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                                   4.0
                                                                                                                                             from TMT
                                                                                                                                                     30     m/s Na layer vel
                                                                                                                                                            um P-P stroke
                                                                                                                                                                                     1.00
                                                                                                                                                                                     1.00
                                                                                                                                                                                     0.98
                                                                                                                                                                                              1.00
                                                                                                                                                                                              1.00
                                                                                                                                                                                              0.99
                                                                                                                                                                                                     1.00
                                                                                                                                                                                                     1.00
                                                                                                                                                                                                     0.99
                                                                                                                                                                                                              1.00
                                                                                                                                                                                                              1.00
                                                                                                                                                                                                              1.00
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                             1.00
                                                                                                                                                                                                                             1.00
                                                                                                                                                                                                                             1.00


   –
                                High-Order Aliasing Error                                                                   18   nm                  44     Subaps                   0.96     0.97   0.98     0.99    1.00   1.00

       Nearby AGN               DM Drive Digitization
                                Uncorrectable AO System Aberrations
                                Uncorrectable Instrument Aberrations
                                                                                                                             4
                                                                                                                            20
                                                                                                                            25
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                                     10
                                                                                                                                                  Alloc
                                                                                                                                                  Alloc
                                                                                                                                                            bits                     1.00
                                                                                                                                                                                     0.95
                                                                                                                                                                                     0.92
                                                                                                                                                                                              1.00
                                                                                                                                                                                              0.97
                                                                                                                                                                                              0.95
                                                                                                                                                                                                     1.00
                                                                                                                                                                                                     0.98
                                                                                                                                                                                                     0.97
                                                                                                                                                                                                              1.00
                                                                                                                                                                                                              0.99
                                                                                                                                                                                                              0.98
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                      0.99
                                                                                                                                                                                                                      0.99
                                                                                                                                                                                                                             1.00
                                                                                                                                                                                                                             1.00
                                                                                                                                                                                                                             0.99


   –
                                DM-to-lenslet Misregistration (all sources)                                                 15   nm               Alloc                              0.97     0.98   0.99     0.99    1.00   1.00

       Gravitational Lenses     Angular Anisoplanatism Error
                                                                                              68 nm
                                                                                                                                0 nm                   0 arcsec                      1.00     1.00   1.00     1.00    1.00   1.00

                                Total High Order Wavefront Error                                                         136 nm                    High Order Strehl               0.10 0.24 0.43 0.64 0.77 0.86

                                                                                            Angular                Equivalent
                              Tip/Tilt Errors                                                                                                         Parameter                                  Strehl ratios
                                                                                           Error (rms)             WFE (rms)

• During requirements           Tilt Measurement Error (one-axis):
                                Tilt Bandw idth Error (one-axis)
                                Tilt Anisoplanatism Error (one-axis)
                                                                                             5.18
                                                                                             0.63
                                                                                             5.99
                                                                                                    mas
                                                                                                    mas
                                                                                                    mas
                                                                                                                            63
                                                                                                                             8
                                                                                                                            73
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                                    17.8
                                                                                                                                                    61.0
                                                                                                                                                    40.2
                                                                                                                                                            mag (mV)
                                                                                                                                                            Hz
                                                                                                                                                            arcsec
                                                                                                                                                                                     0.49
                                                                                                                                                                                     0.98
                                                                                                                                                                                     0.42
                                                                                                                                                                                              0.61
                                                                                                                                                                                              0.99
                                                                                                                                                                                              0.54
                                                                                                                                                                                                     0.73
                                                                                                                                                                                                     0.99
                                                                                                                                                                                                     0.67
                                                                                                                                                                                                              0.83
                                                                                                                                                                                                              1.00
                                                                                                                                                                                                              0.79
                                                                                                                                                                                                                      0.90
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                      0.87
                                                                                                                                                                                                                             0.94
                                                                                                                                                                                                                             1.00
                                                                                                                                                                                                                             0.92

  flowdown & initial            Residual Centroid Anisoplanatism
                                Residual Atmospheric Dispersion
                                Science Instrument Mechanical Drift
                                                                                             1.99
                                                                                             1.06
                                                                                             0.50
                                                                                                    mas
                                                                                                    mas
                                                                                                    mas
                                                                                                                            24
                                                                                                                            13
                                                                                                                             6
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                 nm
                                                                                                                                                        5
                                                                                                                                                       20
                                                                                                                                                    Alloc
                                                                                                                                                            x reduction
                                                                                                                                                            x reduction
                                                                                                                                                            (0.2 mas)
                                                                                                                                                                                     0.87
                                                                                                                                                                                     0.39
                                                                                                                                                                                     0.99
                                                                                                                                                                                              0.91
                                                                                                                                                                                              0.44
                                                                                                                                                                                              1.00
                                                                                                                                                                                                     0.95
                                                                                                                                                                                                     0.84
                                                                                                                                                                                                     1.00
                                                                                                                                                                                                              0.97
                                                                                                                                                                                                              0.96
                                                                                                                                                                                                              1.00
                                                                                                                                                                                                                      0.98
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                      1.00
                                                                                                                                                                                                                             0.99
                                                                                                                                                                                                                             1.00
                                                                                                                                                                                                                             1.00


  design, all performance
                                Long Exposure Field Rotation Errors                          0.50   mas                      6   nm                 Alloc   (0.2 mas)                0.99     1.00   1.00     1.00    1.00   1.00
                                Residual Telescope Pointing Jitter (one-axis)                4.85   mas                     59   nm                    29   Hz input disturbance     0.53     0.64   0.75     0.85    0.91   0.95

                                Total Tip/Tilt Error (one-axis)                             9.61 mas                     116 nm                     Tip/Tilt Strehl                0.22 0.31 0.44 0.59 0.72 0.82
  budgets will be used        Total Effective Wavefront Error                                                            179 nm                      Total Strehl                  0.02 0.08 0.19 0.38 0.55 0.71
  for rapid reevaluation      Sky Coverage                         Galactic Lat.              30 deg



  of performance                Corresponding Sky Coverage

                              Assumptions / Parameters
                                                                                                                       5.0%              This fraction of sky can be corrected to the Total Effective WFE show n




  cost/benefit                                r0
                                              Theta0_eff
                                                                        0.165 m      at this zenith
                                                                         1.98 arcsec at this zenith
                                                                                                                Wind Speed
                                                                                                                Outer Scale
                                                                                                                                   13.67 m/s
                                                                                                                                      75 m
                                                                                                                                                            Zenith Angle
                                                                                                                                                            HO WFS Rate
                                                                                                                                                                                       30
                                                                                                                                                                                    1114
                                                                                                                                                                                            deg
                                                                                                                                                                                            Hz       SH     using    CCD
                                              Sodium Abund.                 4 x 109 atoms/cm 2                  LGS Ast. Rad.       0.08 arcmin             HO WFS Noise              1.7   e- rms
                                                                                                                                                            HOWFS anti-aliasing      NO
                                              Science Target:        SCAO                                                                                   LO WFS rate              915    Hz       SH     using    SNAP
                                              LOWFS Star(s):         MOAO           2 TT            star(s) &                   0 TTFA   star(s)            LO WFS Noise              4.5   e- rms




                              Example for LGS observation of TNO using two galactic M-dwarfs as tip/tilt stars
                                                                                                                                                                                                                             33
   Improving Performance Predictions
• Performance versus Blue Book
   – Delivered system & science instrument didn‟t achieve some
     requirements
   – Environment different than some assumptions
• Why will NGAO performance estimates be better
   – Experience at Palomar, Lick & Keck
   – Better understanding of Keck environment
   – Performance estimation tools more complete & anchored to actual
     performance
• For effects such as multi-guide star tomography for which we don‟t
  have real-world experience:
   – Based on modeling and detailed simulations
       • Comparing & validating these tools (TMT, Gemini, COO, Keck, UCO)
   – Aided by lab experiments (e.g. LAO)
   – Undoubtedly there will be “real-world” effects that we are not yet taking
     into account
                                                                             34
     Keck LGS AO Wavefront Error Budget
                                LGS (10th mag)                        Explanations
                        Blue Book Measured NGAO tool
Atmospheric fitting        123       128       102
Telescope fitting          105        60        70
Camera                      35       113       113   NIRC2 aberrations
DM bandwidth                36       157       143   Lower bandwidth
DM measurement              98       142       135   Lower laser power
TT bandwidth                34       109        30   Vibrations - will be added to NGAO tool
TT measurement              34        23         4
LGS focus error             35        36        25
Focal anisoplanatism       127       175       151   Different atmosphere
LGS high-order error         0        80        80
Centroid anisoplanatism      0         0        21
Atmospheric dispersion       0         0        81
Miscellaneous                0         0         0   Dyn calibs, tel, poorly sensed, atmos disp
Miscellaneous (NGAO)         0         0        53   Seven ~20 nm terms
Calibrations                30         0        40
Total wavefront error      243       358       330
K-band Strehl              0.62      0.35      0.41
Percentile Seeing          50%       75%       65%

                                                                                            35
          NGAO Trade Studies



                          Dekany
To date: Bauman, Clare, Gavel, Flicker, Kellner, Neyman, Velur
                  Design Trade Studies
• Trade studies were initiated at the start of System Design phase
• We have completed or nearly completed:
    –   Methods of mitigating laser Rayleigh backscatter
    –   Laser guide star asterism & geometry
    –   Multi-Object (MOAO) & Multi-Conjugate (MCAO) architectures
    –   Variable vs fixed laser asterism on the sky
    –   Fast tip/tilt opto-mechanical implementation options
    –   Low order wavefront sensor type & number
• Additional design studies now underway include:
    –   LGS wavefront sensor architecture & type
    –   Science instrument re-use
    –   Telescope static & dynamic errors
    –   Interferometer support
    –   Sodium return versus laser format

                                                                     37
    Mitigating Laser Rayleigh Backscatter
• Evaluate impact of unwanted Rayleigh backscatter on
  NGAO system performance
• Status:
   – Evaluated the intensity of the Rayleigh as well as aerosol and
     cirrus backscatter as seen at the Keck focal plane
   – Surveyed the available lasers and pulse formats
   – Surveyed methods of blocking Rayleigh
   – Interim results at NGAO meeting 3 (12/13/06)
• Best rejection choice: appropriately pulsed laser which
  can have a gated return so that almost no Rayleigh
  background is encountered
• However, most powerful & promising lasers in terms of
  sodium return per Watt, are CW

                                                                      38
             LGS Asterism & Geometry

• Find the simplest LGS
  asterism geometry meeting
  the performance budget
  goals
   – Number of guidestars
   – Constellation configuration
   – Constellation size
• Conclusions
   – Simulations of tomography
     generally validate the
     theoretical scaling laws
   – 5 LGS constellation works
     ok on 20 arcsec field
   – 7-9 LGS will be needed on
     90 arcsec field
• KAON 429

                                       39
           Multi-Object vs Multi-Conjugate AO
•       Understand potential risks, technical challenges, limitations, advantages &
        room for improvement with Multi-Object (MOAO) & Multi-Conjugate (MCAO)
                               Laser
                                                                       Laser                                         Laser
                                                                       Beams                                         Beams
       MCAO                    Beams
                                          MOAO                                              Hybrid
                                                     LGS
                                                   Wavefront
                                                   Sensors
                                                                       Dichroic
                                          Tomography
                                          Computer
                  Dichroic                                                                              Dichroic
                             Deformable                                                                            Deformable
                                                                  DM     DM
    Science                  Mirrors                                                      Science                  Mirrors
    Instruments                                                                           Instruments
                             Tomography                                                                            Tomography
                             Computer                                                                              Computer
          LGS Wavefront                                Science                 Science          LGS Wavefront
          Sensors                                      Detector                Detector         Sensors



•       Calculated performance for 1, 2 & 3 DM MCAO systems & compared to
        small sub-field IFU or imager arms, each with a DM
•       Conclusions:
           – MCAO offers a contiguous field for imaging, but a large error term. “Generalized
             anisoplanatism” dominates in wide-field cases
           – MOAO greatly reduces anisoplanatic error at cost of non-contiguous field
•       KAON 452

                                                                                                                                40
                        Summary
• Management update:
   – Systems Engineering Management Plan in place
   – Executive Committee working well together
   – Ramp up slower than planned, but team & processes now in
     place
   – Good technical progress is being made
• Technical update:
   – Iterations between science requirements & performance budgets
     are achieving our goals of understanding what is really needed
   – Learning what we need to from architecture trade studies
   – Building base for design choices & cost/benefit trades

    We now have the management structure, plan & enthusiastic
         team to produce an excellent NGAO System Design.

                                                                 41

				
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