““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