NGAO Instrumentation
Preliminary Design Phase Planning
September 2008
Sean Adkins
Overall Approach
• Priorities
– Support PDR success
• Design and build to cost objectives
• Systems engineering goals
• Interface definitions
– Move instrument designs forward
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Address most challenging design aspects
Develop firm interface definitions with AO system
Support other design activities
Develop full plans for design and fabrication
• Initial Plan
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Limited in scope due to funding uncertainty
Focused on “minimum” needs to support AO system design
Pragmatic, based on heritage designs and proven concepts
Takes advantage of design overlaps between imagers
Seeks to develop synergy for probe arms between TT and d-IFS
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PD Phase Objectives for Instruments
• Overall
– Instrumental wavefront error budget and internal wavefront error
allocations for the instruments
– Strategies for controlling and minimizing instrumental wavefront error
– Science driven pixel scale requirements and basis for implementation
– AO system to instrument alignment requirements and methodology
– Calibration requirements and methodology
– Firm interface definitions for optical, mechanical, electronic and software
interfaces for the instruments
– Virtual instrument definition for the NGAO master command sequencer
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PD Phase Objectives for Instruments
• Imagers
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Wavelength ranges for the visible and near-IR imagers
Sensitivity error budgets for the visible and near-IR imagers
Coronagraph performance and companion sensitivity
Visible IFU conceptual design and feasibility assessment
Optical design to at least a PD level for both instruments
Conceptual design for mechanical systems and thermal systems
Software requirements
Best effort costing
• d-IFS
– Ensquared energy and throughput budgets
– Performance estimates for slicer and spectrograph
– PD level probe arm design in collaboration with the near-IR TT sensor
probe arm design
– First cut optical design
– Conceptual design for mechanical systems and thermal systems
– Software requirements
– Best effort costing
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Key Issues
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Design pre-requisites
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Initial AO System to instrument interface definitions
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Optical (first draft in KAON 555)
Mechanical (first draft in KAON 555)
Electronic/Electrical (very straightforward, heritage based)
Software (relatively straightforward, likely heritage based)
Alignment and calibration concepts for instruments on AO System
Trade studies
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AO system narrow field optical characteristics
Confirmation of available envelope and mounting configuration for instrument
AO and Instrumental Wavefront Error
Pixel Scale
Short Wavelength cut-off
IFU Capability (visible imager)
Ensquared energy (d-IFS)
Performance and error budgets
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Sensitivity
Background
Companion Sensitivity
Wavefront Error
Probe Positioning Performance (d-IFS)
Size and Mass
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Initial Project Plan
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Initial Resource Requirements
• 124 hours of interface related effort in v17 NGAO project plan
• Resources for proposed plan:
Resource
Sean Adkins
Science Lead
Science Team
Optical Engineering
Mechanical Engineering
Software Engineer
WMKO Support Astronomer
WMKO Software Staff
WMKO Instrument Staff
WMKO Electronics Staff
Hours
1019
723
160
1624
1911
200
60
60
60
60
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