MAORY ADAPTIVE OPTICS Laura Schreiber, Carmelo Arcidiacono, Giovanni Bregoli, Fausto Cortecchia, Giuseppe Cosentino (DiFA), Emiliano Diolaiti, Italo Foppiani, Matteo Lombini, Mauro Patti (DiFA-OABO)
MAORY E-ELT Multi Conjugate Adaptive Optics Relay Wavefront sensing based on 6 Sodium LGS and 3 NGS Wavefront Correction operated by M4/M5 (Telescope) and 2 Post focal deformable mirrors conjugated at 5 km and 12.7 km MCAO and SCAO modes MAORY Consortium
Adaptive Optics 4 dummies Reference Star Science Object Deformable Mirror Distorted Wavefront Control System Beam Splitter Corrected Wavefront Wavefront Sensor
Adaptive Optics 4 dummies Reference Star Science Object Deformable Mirror Distorted Wavefront Control System Beam Splitter Corrected Wavefront Wavefront Sensor
Adaptive Optics 4 dummies Actuator Perturbation Control System Servo System Sensor
Product Tree DMs RTC LGS WFSs NGS WFSs DM : Deformable Mirror RTC : Real Time Computer WFS : Wavefront Sensor LGS : Laser Guide Star NGS : Natural Guide Star 6
Classical Adaptive Optics (SCAO) Science target Reference Source 1 DM corrects the total effect of turbulence in the reference source direction at the telescope entrance level
Classical Adaptive Optics (SCAO) Science target Reference Source 1 DM corrects the total effect of turbulence in the reference source direction at the telescope entrance level The correction in the direction of the science target gets worse increasing the angular distance between the science target and the reference source, because the two atmospheric cilinders are more and more different
Classical Adaptive Optics (SCAO) Science target Reference Source (RS) This translates into a deformation of the PSF across the FoV that depends on the distance from the guide star. 1 DM corrects the total effect of turbulence in the reference source direction at the telescope entrance level SCAO: Small corrected FoV Low Sky coverage PSF variability
SCAO PSF Variation FLAO@LBT J band 16 10
Multi Conjugate Adaptive Optics (MCAO) Reference Source Science target Reference Source Multiple Reference Stars For a tomographic measurement of the tubulence Multiple DMs correct the turbulence at the altitudes where the turbulence is more powerfull MCAO: Large corrected FoV Low Sky coverage PSF stability
What s LGS MCAO? Science target Artificial Reference Sources LGSs : Artificial reference sources can be created to ensure high sky coverage Multiple DMs correct the turbulence at the altitudes where the turbulence is more powerfull MCAO: Large corrected FoV High Sky coverage PSF stability
What s LGS MCAO? Science target Artificial Reference Sources LGSs : Artificial reference sources can be created to ensure high sky coverage But the laser light has to cross the atmosphere twice, causing some complication Multiple DMs correct the turbulence at the altitudes where the turbulence is more powerfull MCAO: Large corrected FoV High Sky coverage PSF stability
What s LGS (+ NGS) MCAO? Reference Source Science target Artificial Reference Sources NGS : A natural Source is required to misure fast tip/tilt LGSs : Artificial reference sources can be created to ensure high sky coverage Multiple DMs correct the turbulence at the altitudes where the turbulence is more powerfull MCAO: Large corrected FoV High Sky coverage PSF stability
What s LGS (+ NGS) MCAO? sodium layer dh = 10km H=90km Atmosphere Telescope Pupil Wavefront Sensor
Sodium layer profile features Picture taken from: T. Pfrommer and P. Hickson, 2010, J. Opt. Soc. Am. A Vol. 27 No. 11 Impact of mean altitude variations: On 40 m telescope, 7 nm defocus per meter of altitude change Focus effect is big and fast and requires measurement by fast TTF WFS
What s LGS (+ NGS) MCAO? Reference Source MCAO NGSs : Multiple natural Sourcea are maybe needed to misure fast tip/tilt and slow high order modes LGSs : Artificial reference sources can be created to ensure high sky coverage Science target Artificial Reference Sources Reference Source Multiple DMs correct the turbulence at the altitudes where the turbulence is more powerfull MCAO: Large corrected FoV High Sky coverage PSF stability
MAORY 4 dummies Reference Star Science Object Deformable Mirror Distorted Wavefront Control System Beam Splitter Corrected Wavefront Wavefront Sensor
MAORY 4 dummies Gain in resolution: K band, seeing disk 0.5 (FWHM), MAORY PSF 11 mas (sorrounded by a seeing halo containing 70% of the light) 19
Key components Deformable mirrors Telescope M4 (deformable) Telescope M5 (Tip-Tilt) 2 post focal 2 equals mirror (concave or flats) 700 mm diameter (29 mm actuator spacing) Voice-coil motor actuators: Matching with MAORY requirements Commonalities with E-ELT M4 Wavefron sensors 6 SH LGS WFSs 80X80 500 Hz (detector 800X800 px 10 px FoV) multiple NGS measuring: fast (100 500 Hz) Tip-Tilt, Focus and astigmatisms, Shack-Hartmann infrared sensor Slow (0,1 Hz) low/medium ( 50 modes) order modes variations, NXN subapertures (TBD) in the optical range (0.6-0.9 µm). (Arcetri group) 20
Key components Real Time computer Real time means deterministic Deterministic means that tasks has to be executed with the right timing Scheduling management moreover it has to be fast Low latency Hardware choice GPU, FPGA, Multi Integrated Core tecnology (Xeon Phy) Smart/Fast interfaces Smart/Fast interconnects Software optimization Some numbers for MAORY Matrix Vector Multiplication: 10 9 elts, every 2 ms Pixel handling: 10 Gbps per WFS 21
Product Tree Engineering L. Schreiber (OABO) E. Cascone (OACdM) A. Baruffolo (OAPD) Adaptive Optics Electronic Eng Software Eng Design L. Schreiber (OABO) I. Foppiani (OABO) E. Cascone (OACM) C. Felini (OACM) G. Cosentino (DiFA) A. Baruffolo (OAPD) G. Bregoli (OABO) 22
MAORY AO system Engineering WP Manager: Carmelo Arcidiacono Persons Involved: C. Arcidiacono, L. Schreiber, M. Patti (OABO - DIFA), S. Oberti (ESO), G. Bregoli Output: AO system analysis and performance, E2E simulation code, PSF and Sky coverage, Error Budget (+ input to other common outputs) MAORY MAO: necessary tool for such a complex system design, in order to assure the scientific requirements fullfillment System dimensioning and optimization Key/critical components design (WFS detectors, DMs ) Operation/calibration/control strategy evaluation External disturbances impact (telescope residual wavefront errors, wind shake, reference sources elongation, nasmith vibrations) Error budget 23
AO system modelling System parameters setup Atmospheric Layers generation Wavefronts generation Telescope aberrations Influence functions Interaction Matrix calibration Control Matrix End-to-End simulation code Modular structure Accurate mode / fast mode High-level IDL / Low level CUDA on 4 GPUs LGS modelling Detailed sodium layer modelling including variation Input disturbances Atmosphere, telescope, etc. Closed Loop correction PSF computation
AO system modelling MAORY LGS channel prototype Phase screens Shack Hartmann WFS 40X40 Elongated sources Simulation validation 25
Waiting for the first light 26