Docstoc

Canary Phase A FDR

Document Sample
 Canary Phase A FDR Powered By Docstoc
					The on-sky NGS/LGS MOAO
  demonstrator for EAGLE

        Tim Morris
       Durham University
                        Talk overview

   MOAO with EAGLE
   CANARY concept
   Optomechanical design
   Subsystem performance
   System performance
   System calibration tasks




AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                      MOAO with EAGLE

   With the current baseline design, EAGLE will:
        use 6 LGS and up to 5 NGS to map the turbulence above the E-
         ELT
        correct up to 20 x ~2” diameter science fields anywhere within
         the central 5’ diameter field using open-loop AO
        250Hz frame rate
   E-ELT has a deformable ‘secondary’ that will be used as
    a closed-loop woofer (GLAO-like DM)
        EAGLE is both a closed and open-loop system
   30% ensquared energy with 75mas (H-band) required
    performance


AO4ELTs, Paris 2009    CANARY: NGS/LGS MOAO demonstrator     Tim Morris et al
         MOAO with EAGLE: big questions
   Can we achieve tomographic reconstruction to the required
    accuracy over such wide fields?
   Can we reliably control a DM in open-loop?
   How do we calibrate the system?
   How accurately do we need to measure the Cn2 profile to optimise performance?
   What is the impact of running the system with both open and closed loop DMs?
   How do we compensate for LGS specific effects that can impact MOAO
    performance?
   What are the principle performance drivers required when designing an MOAO
    system?
   What is the best way to combine both NGS and LGS WFS signals to measure
    tomography?
   Answer as many of these questions as possible as soon as possible
    to feed into the EAGLE design
        Some can be (and have been) answered in simulation or using a lab
         system such as SESAME

AO4ELTs, Paris 2009      CANARY: NGS/LGS MOAO demonstrator              Tim Morris et al
                      CANARY concept




AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                        CANARY Aims

   Perform NGS then LGS based tomographic WFSing
   Perform open-loop AO correction on-sky
   Develop calibration and alignment techniques
   Fully characterise system and subsystem performance

   Create a single MOAO channel EAGLE as closely as
    possibly using the 4.2m William Herschel Telescope
        Effectively a 1/10th scale model of E-ELT using a 10km Rayleigh
         LGS




AO4ELTs, Paris 2009    CANARY: NGS/LGS MOAO demonstrator      Tim Morris et al
         CANARY phased development

   Based around a set of reconfigurable optical
    modules to allow ‘easy’ changes between three
    CANARY phases
        Phase A: Low-order NGS-only MOAO (2010)
        Phase B: Low-order LGS MOAO (2011)
        Phase C: High-order LGS + NGS MOAO (2012)


   All phases will include an extensive calibration
    and diagnostics package

AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
    Diagnostics and Performance monitoring
 On-axis NGS WFS behind AO corrected focal plane
  (Truth Sensor)
 On-axis NIR imaging camera (Science Verification
  Camera)
 High-order high-bandwidth DM figure sensor
 SLODAR analysis performed using open-loop WFSs
 External turbulence profilers
        SLODAR
        MASS-DIMM
   Telescope simulator
        Turbulent phase screens
        NGS and LGS alignment and calibration sources


AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                           Phase A : NGS MOAO
   Components:
         Low-order 8x8 DM                                                 10" Truth sensor
         3 x L3CCD open-loop NGS WFSs                                     & IR camera FOV
         Open-loop optimised Fast Steering
          Mirror                                                                              NGS WFS
         Hardware accelerated Real Time                        NGS WFS
          control system
         NGS MOAO Calibration Unit
                                                                               NGS WFS
    Phase A: NGS MOAO                                        Science
                                                            Verification
                                        NGS     Low-order
 WHT         GHRIL           NGS
                                        FSM       DM
                                                                                                 2.5’
Nasmyth     Derotator       Pickoffs
                                                             Truth                            Derotated
                                                             Sensor
                                                                                              WHT field
             Calibration    3 x NGS              Figure
                Unit          WFS                Sensor




    AO4ELTs, Paris 2009           CANARY: NGS/LGS MOAO demonstrator                   Tim Morris et al
            Phase B: Low-order LGS MOAO
    GLAS       Diffractive     LGS      GLAS             Figure        3 x NGS
     BLT         Optic        Rotator   Laser            Sensor          WFS

                              LGS        NGS         Low-order              NGS
 WHT          GHRIL                      FSM                               Pickoffs
                             Dichroic                  DM
Nasmyth      Derotator

                               LGS
              Calibration    Pickoffs      Science                Truth
                 Unit                     Verification            Sensor
                                                                                      1.5’ Diameter
Phase B: Low-order
                              LGS
                              FSM
                                                                                      LGS asterism
   LGS MOAO
                             4 x LGS
                               WFS


   New modules include:
          Electronically shuttered LGS WFS CCD
          Modified GLAS launch system
          LGS dichroic and relay system
          LGS MOAO Calibration Unit
    AO4ELTs, Paris 2009           CANARY: NGS/LGS MOAO demonstrator                   LGS WFS et al
                                                                                        Tim Morris
             Phase C: High-order LGS MOAO
          GLAS        Diffractive    LGS         GLAS                                    Figure
           BLT          Optic       Rotator      Laser                                   Sensor



       WHT            GHRIL         NGS       Low-order    LGS        NGS                MEMS
      Nasmyth        Derotator      FSM         DM        Dichroic   Pickoffs             DM


                     Calibration                            LGS      3 x NGS
                        Unit                              Pickoffs     WFS

                 Phase C: High-order woofer-tweeter        LGS                   Science          Truth
                 LGS MOAO (woofer closed loop)             FSM                  Verification      Sensor


                                                          4 x LGS
                                                            WFS



    Closest resemblance to proposed EAGLE MOAO implementation
    Largest upgrade here is to the RTCS. From Phase B we have:
          ~ 2 times increase in pixel bandwidth
          ~ 5 times increase in slope bandwidth
          ~ 17 times increase in actuator bandwidth
    AO4ELTs, Paris 2009             CANARY: NGS/LGS MOAO demonstrator                             Tim Morris et al
                 Optomechanical design




AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                      Phase A optical design
                        Output focal plane             Truth Sensor focal plane




      Input Focal Plane           Science Verification Camera focal plane
AO4ELTs, Paris 2009       CANARY: NGS/LGS MOAO demonstrator          Tim Morris et al
                      Phase B optical design
     LGS TT mirror




   Acquisition camera moved to              NGS WFS placed at
         input focal plane                  corrected focal plane
AO4ELTs, Paris 2009      CANARY: NGS/LGS MOAO demonstrator          Tim Morris et al
         Phase C optical design concept




    LGS WFS(s) moved behind               Possible locations of
        closed-loop DM                     MEMS MOAO DM
AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator           Tim Morris et al
                      NGS WFS Assembly




AO4ELTs, Paris 2009    CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                      Telescope Simulator




AO4ELTs, Paris 2009    CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                Subsystem performance




AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                      Open-loop DM Control

   4% open-loop error with hard PZT DM demonstrated in
    laboratory with SESAME
        40nm RMS error if a 1000nm RMS DM surface is requested
   Figure sensor could be used to control any long term
    drifts in DM surface shape
        Will introduce some additional latency
        Has been used with a Xinetics DM and produces a similar
         surface error to the hard PZT DM
   Open loop control of a DM doesn’t seem to be a problem
    for CANARY low-order DM
        High-order MEMS DM open-loop control has already been
         demonstrated

AO4ELTs, Paris 2009     CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
    Subsystem performance: LGS Launch
 Test system installed on WHT and tested in May
 Uses DOE in GLAS launch system to create a 4 star asterism (MMT
  approach)
 Several possible asterisms available by changing DOE
        10 to 90” diameter asterisms (takes about 15 minutes)
   80% of light into 4 diffracted LGS beams but altitude is lowered c.f. GLAS
        Still want an upgraded laser to increase WFS SNR
   Software problem with LGS detector meant range gated images couldn’t be
    obtained




Non-gated image of ~40” LGS                    DOE mounted in rotation stage at
  radius asterism at 6.7km                          GLAS BLT entrance
AO4ELTs, Paris 2009       CANARY: NGS/LGS MOAO demonstrator           Tim Morris et al
                                 RTCS

   Hybrid FPGA-CPU Realtime Control System
        FPGA pixel processing developed for HOT and SPARTA
        Reconstructor in CPU
        DM control in CPU
   Currently runs at Phase A/B at 300-400Hz using a single
    threaded reconstructor pipeline
        Latency and jitter to be measured
   Upgrade required to cope with high-order LGS WFSs
    and DM in Phase C
        Parallelise reconstructor
        GPU acceleration


AO4ELTs, Paris 2009    CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                      RTCS overview




AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                      System performance




AO4ELTs, Paris 2009     CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                       Phase A Performance
 Monte-Carlo simulations performed using independent codes in Durham
  and Paris
 Single open-loop DM
          8x8 actuators
          DM (and science path) on-axis
    3 x NGS WFSs
          Off-axis (30” to 90”)
          7 x 7 subapertures
          0.1e- read noise
          Mv = 8 to 14
          250Hz frame rate
    Representative summer La Palma turbulence profile used1
          r0 = 12cm
          45% @ 0km
          15% @ 2.5km
          30% @ 4km
          10% @ 13.5km

1   Fuensalida et al, RevMexAA, 31, 84-90 (2007)
AO4ELTs, Paris 2009           CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                   Simulated Performance
              Source of error                              WFE (nm rms)
WFS open-loop estimation                    63 (from YAO)
WFS noise (quantum + readout)               40 at mR=10
                                            80 at mR=12
                                            190 at mR=14
Tomographic reconstruction (30’’ radius)    260 (GLAO least-square)
                                            220 (tomographic least square)
                                            170 (L&A MMSE) (Vidal et al)
DM fitting                                  140
DM open-loop error                          48
Tip-tilt open-loop error                    26
Temporal and aliasing                       113
Residual high-orders from optics            50
TOTAL                                       mR=12 : 285 to 340



AO4ELTs, Paris 2009        CANARY: NGS/LGS MOAO demonstrator              Tim Morris et al
                              Error terms
   Principle term is tomographic reconstruction
    error
        30” radius means metapupils at highest turbulent
         layer are almost completely separated
        30” is still pretty small to find a 4-star mv = 12
         asterism
   Have identified several suitable targets within a
    2.5’ diameter FOV observable between June-
    October
   Will be even worse with the 10km Rayleigh LGS
    at Phases B and C
        Requires the external turbulence profiling to
         determine how much of the turbulence is above
         the LGS
   The Truth Sensor will be used as the principle
    system diagnostic
        Science camera can be used when the
         turbulence cooperates
        >60% turbulence in the ground layer is often
         observed at the WHT
AO4ELTs, Paris 2009      CANARY: NGS/LGS MOAO demonstrator    Tim Morris et al
                      System Calibration




AO4ELTs, Paris 2009    CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                          Phase A calibration
   Interaction matrix measurement using a
    reverse path calibration source
         On-axis point source pointing backwards at        NGS WFS pickoff prism
          output focal plane can be observed by each
          NGS WFS in turn                                       From reverse path
         Requires stable pupil image at lenslet array          calibration source
          across full FOV

   Or use TS to measure DM influence functions
         Observe ground-layer only turbulent sources                                  To
          within the telescope simulator with NGS WFSs                                 WFS
          and TS
         Translate TS measure influence functions to
          each DM

   Or measure matrices on-sky                              From telescope
         Learn and Apply method from Fabrice Vidal first
          thing this morning

    AO4ELTs, Paris 2009     CANARY: NGS/LGS MOAO demonstrator            Tim Morris et al
                      Other calibration tasks
   Field dependent aberrations
        Pupil image stability is <1/100th pupil diameter
        Monitoring and compensation changing field aberrations
   Non-common path error compensation
        Deployable point sources in most focal planes
        Some pointing backwards for reverse path calibration
   WFS linearity/gain optimisation (for WCOG etc.)
        Use sources in NGS focal plane
   NGS pickoff positioning accuracy
        Confirm with full field acquisition camera
   Detector calibration
   At Phase B/C:
        LGS WFS offsets/centroid gain
        Range gate setting and optimisation
        LGS WFS interaction matrix
   To be developed further during the Integration and Testing phase
        Runs from October 09 – April 10


AO4ELTs, Paris 2009        CANARY: NGS/LGS MOAO demonstrator      Tim Morris et al
                          Conclusions
   Already answered some of the big questions that MOAO
    with EAGLE raises
        Open-loop DM control
        Several calibration schemes proposed
   CANARY will have the capability to answer the
    remaining ones by demonstrating and testing wide-field
    LGS tomographic AO
   Critical subsystems are being testing and the initial
    integration phase is about to begin
   We’re on track to go on-sky mid 2010 with the Phase A
    NGS tomography experiment
   Phase B design to be reviewed at the end of this year

AO4ELTs, Paris 2009   CANARY: NGS/LGS MOAO demonstrator   Tim Morris et al
                      The CANARY team
  Durham                  Richard Myers, Gordon Talbot, Nigel Dipper, Deli Geng, Eddy
                          Younger, Alastair Basden, Colin Dunlop, Nik Looker, Jonny
                          Taylor, Mark Harrison, Tim Butterley, Dani Guzman, Laura
                          Young, Simon Blake, Sofia Dimoudi
  Obs. Paris              Zoltán Hubert, Gerard Rousset, Eric Gendron, Fabrice Vidal,
                          Damien Gratadour, Aglae Kellerer, Michel Marteaud, Fanny
                          Chemla, Phillipe Laporte
  UKATC                   Andy Longmore, David Henry, Stephen Todd, Colin Dickson,
                          Brian Stobie
  ONERA                   Thierry Fusco, Clelia Robert, Nicolas Vedrenne

  ING                     Jure Skvarc

  PUC Santiago            Andres Guesalaga

  Herriott-Watt           Alan Greenaway, Heather Dalgarno

  Engineering and         Kevin Dee
  Project Solutions Ltd
AO4ELTs, Paris 2009       CANARY: NGS/LGS MOAO demonstrator                Tim Morris et al
                      CANARY capabilities
   CANARY can:
        Perform, calibrate and characterise accuracy of open-loop LGS
         tomography on-sky
        Measure/monitor everything to make sure we understand performance
         of each component as well as the system as a whole
        Develop alignment and calibration techniques
        Combine several off-axis NGS and LGS WFSs to map the turbulence
        Eventually use a closed-loop woofer and open-loop tweeter
        Emulate arbitrary LGS intensity profiles and elongation
   CANARY cannot:
        Reach EAGLE performance goal
        Match the total number of subapertures/actuators within EAGLE
        Match the exactly LGS/NGS FOV afforded by the E-ELT
        Take advantage of the multiplex normally afforded by MOAO – only a
         single channel

AO4ELTs, Paris 2009     CANARY: NGS/LGS MOAO demonstrator         Tim Morris et al

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:13
posted:8/13/2010
language:English
pages:32