Adaptive Optics Systems Engineering on GMT. Peter McGregor. Will GMT queue schedule instruments? What instrument configuration time is acceptable? Will GMT have general-purpose ports ? What field of view? Will the upper IP support non-AO instruments ? What field of view? - PowerPoint PPT Presentation
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Adaptive Optics Systems Engineering on GMT Peter McGregor
PSWG March 2008
Top-Level Questions:Will GMT queue schedule instruments?What
instrument configuration time is acceptable?Will GMT have
general-purpose ports?What field of view?Will the upper IP support
non-AO instruments?What field of view?What acquisition/calibration
support?Will M1/M2 be phased intrinsically?If extrinsic, what
FoV/magnitude star is required?What are the advantages of using an
ASM?What is optimal AO instrument performance?How can maximum AO
sky coverage be achieved?What TTWFS patrol field?Yes5 minYes5
arcminYes5 arcminFullYes?TBDTBDTBDTBD
PSWG March 2008
Proposed Solution:5 arcmin folded Gregorian focus on upper IP+/-
75 arcsec AO engineering field+/- 30 arcsec AO science
fieldIntegrated acquisition and calibration facilitiesMultiple
(4-6) non-AO & AO instrument portsRapid reconfiguration between
instrumentsMaximum cryogenic AO system and instrumentsMaximum AO
tip-tilt WFS patrol fieldMinimum interference in science path
PSWG March 2008
New ASM AO ParadigmInstrumentAcqCamNGS WFSLGS WFSPhasing
CamT-T-FWFSTruth WFS
PSWG March 2008
Outstanding Issues:Does M1 phasing require a 10 arcmin patrol
field?Does this invalidate the concept?Or does it demand an
intrinsic telescope solution?How should field/pupil rotation be
compensated?Large diameter ferro-fluidic hermetic
seals?Implications for servicability?How to calibrate LGS AO system
with ASM?Are non-common path phase errors acceptable?Where to
locate the IR instrument cold stop?Should GMACS/NIRMOS have
exclusive access?Do they restrict on AO designs?
PSWG March 2008
Non-AO Support RequirementsMultiple (6?) instrument ports5
arcmin diameter FOV2 Peripheral Wave Front SensorsMaintain
independent tip-tilt-focus of 7 M1 segmentsActive optics
monitoringInstrument rotator monitoringAcquisition cameraInstrument
(& WFS) calibration unit
Complete Instr. Support UnitPhasing CameraNGS WFSLGS
WFSCalibration Unit3.5 m
PSWG March 2008
Complete Instr. Support Unit
PSWG March 2008
At Second FocusTip-tilt-focus wave front sensors for LTAOTruth
wave front sensorMinimize non-common path errorsScience
instrument
All with field derotation
PSWG March 2008
Full AO System + GMTIFS
PSWG March 2008
SummaryDemonstrated a feasible implementation of AO at the f/8
Gregorian focusOptics are large and complexConsequences of moving
to an f/16 feed should be consideredMore work is required
to:Improve optical performanceDevelop concepts for science
instruments (GMTIFS, MOAO, MCAO)Include WFSs at second focusAddress
field derotation on a stationary Instrument PlatformConsider 10
arcmin(?) diameter phasing camera patrol field
