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““Riding the Hub”: The MMT Adaptive SecondaryRiding the Hub”: The MMT Adaptive Secondary
Douglas MillerUniversity of Arizona
• The AO System• Current Performance of the MMT AO System• Ongoing Development• Science Instruments
Searching for Exrasolar Systems
The MMT AO NGS TeamThe MMT AO NGS Team
Vidhya Vaitheeswaran
SoftwareEngineer
Matt KenworthyInstrument Scientist
Doug MillerManager
Richard SosaTechnician
Guido BrusaMirror Scientist
Manny MontoyaTechnician
Phil HinzPI
Thomas StalcupAO Scientist
• IR observations are often limited by background light from the telescope optics.•Typical AO systems have background emission of ~20%•A deformable secondary system can have an emissivity of ~5-7%.•This can translate into 3-4x speed improvement in observations.
Advantages of a Deformable Secondary
Thermally Clean PupilThermally Clean Pupil
Images taken at 11 microns of the MMT adaptive secondary.Emissivity of the telescope was measured at 7%.
Emission fromsky
Blackbody emissionFrom central hole in primary
Emission fromsky and telescope
Camera with cold pupil stop misaligned.
Camera with cold pupil stop aligned.
The MMT AO The MMT AO SystemSystem
1. Measure aberrationsdue to the atmospherewith WFS Camera
2. Calculate secondaryshape needed to correctmeasured aberration
3. Apply shape to thedeformable secondaryLoop run
at 550 Hz
WFSCamera
ReconstructorComputer
AdaptiveSecondary
Mirror
12x12 Shack-HartmannSensor
Correct 56 modes
Send new position commands
to the 336 actuators
Current PerformanceCurrent Performance
We typically achieve 20-30% Strehl in H band on bright stars, measured with an engineering camera installed in the AO top box.
Limiting magnitude is V~14.5
Curves are loop speeds of 550, 275, 137 and 68 Hz
Performance -vs- ModePerformance -vs- Mode
Above 60 modes we do not see improved Strehl
Need an improved interaction matrix
“Reconstructor on the sky” technique currently being developed (Brusa et al. Glasgow SPIE 2004)
Expected Strehl
2T02
3T02
1T03
2T03
3T03
1T04
2T04
3T04
1T05
2T05
3T05
1T06
2T06
02.5
57.510
12.515
17.520
22.525
27.5
3032.5
35
M M TAO night a llocation
S cienceE ngineering
Trim ester
Nig
hts
2002 2003 2004 2005 2006
First light obtained November 2002 Science observations interspersed starting in Jan. 2003. Runs were scheduled once per trimester through 2004. Two runs per trimester since January 2005.
Ongoing DevelopmentOngoing Development
Transition of AO System to Facility Instrument Calibration Stand PC-based Reconstructor Computer Rayleigh Laser Guide Stars (Stalcup, Baranec and Lloyd-
Hart talks later today)
Facility InstrumentFacility Instrument
MMT staff will perform normal NGS AO operation Installation of DM and NGS topbox• Operation of AO system for observers• Routine system maintenance• Software maintenance
Transition complete by early 2007 (hopefully) AO Team will continue development and improvements
PC Reconstructor ComputerPC Reconstructor Computer
Current Reconstructor is a VME system written in Assembler (1990s technology)
Replacement is a dual processor PC-based system written in C under standard Linux.
Latencies of ~200 usec are achievable with straightforward implementation. Much more flexible.
Lab tests are complete. On-Sky test will take place Sunday night.
PC Reconstructor ComputerPC Reconstructor Computer Speed up AO loop (~1 kHz) Input accelerometer information into the AO loop to
compensate for the 20 Hz vibration Chop with AO secondary Test new algorithms
Calibration Calibration StandStand
The DM is convex! Test stand uses a Hindle
optical test to measure the surface shape of the DM
All lenses in the test stand are spherical
Allow us to calibrate the flat position • The current gap
(40 microns)• A new gap (100
microns) needed for chopping with the DM
Deformable Mirror
Spherical Calibration
Mirror
Interferometer Interferometer
22 inch fold flat
Optical Rays
4D Interferometer
Calibration Mirror
L2 Lens
L1 Lens
2 Inch Flat
DM Shell
DM Calibration Stand-DM Calibration Stand-Mechanical DesignMechanical Design
Calibration StandCalibration Stand
MMTAO Science CamerasMMTAO Science CamerasARIES: 1-2.5 m
imagerMIRAC-BLINC: 7-25 m imager and nuller
Clio: 3-5 m imager
Jupiter at 4.8 m
Protoplanetary Nebula at 9.8 and 11.7m
IC 2149 at 2.1 m
Don McCarthyDon McCarthy Suresh SivinandamSuresh Sivinandam Bill HoffmannBill HoffmannCraig KulesaCraig Kulesa Ari HeinzeAri Heinze Phil HinzPhil Hinz
Phil HinzPhil Hinz
New and Improved InstrumentsNew and Improved Instruments
Purple: “Old” 1.0-2.5 micron Imager
Green: “New” 1.0 - 5.0 micron echelle spectrometer
Don McCarthy and Craig Kulusa
New MIRAC IV 256x256 array (old 128x128) Lower dark current 8-13 micron grism spectrometer Phil Hinz and Bill Hoffman
Phil
Hub VibrationsHub Vibrations
June 2005 elevation 43 degrees wind velocity 10 mph wind direction 241 degrees azimuth 124 degrees => Out of the wind
June 2006 elevation 60 wind velocity 27 mph wind direction 45 degrees azimuth 315 degrees => Out of the wind
See John Codona’s talk: ??
PSF sidelobes are over 7 magnitudes fainter at 3 /D away.
The pattern is stable and can be reliably subtracted off to reach the limit of the sky background.
PSF suppression is easier at M band where Strehls are typically 90%
John Codona and Matt Kenworthy
Diffraction Suppression via Phase ManipulationDiffraction Suppression via Phase Manipulation
PSF with no Phase Manipulation
You too can
“Ride the Hub” at
http://www.mmtao.org