PFIS Progress Report SALT SWG, 30 Aug, 2000 K. Nordsieck

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PFIS Progress ReportSALT SWG, 30 Aug, 2000K.
Nordsieck

• Status of definition study
• Optical tradeoffs - results
• Mechanisms and control
• Structure
• Budget

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Status of definition study

• Develop the structure and electronics concept
  farther in order to provide more reliable basic
  interface requirements (weight, envelope, power,
  cabling, etc) for the PFIP.
• Still working on it
• Study the effects of pupil size and focal ratio
  on PFIS size/ cost/ performance, for input into
  decision in September.
• Done
• Develop a more accurate cost estimate, with
  margins, for the design and construction phases.
  
• Still working on it

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Optical Tradeoffs - Pupil and F-Ratio

• Effective area peaks at 12 m
• Another figure of merit throughput resolution
• area / pupil
• peaks lt 10.5 m
• Suggest 11 m

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Design Updates

• Extend wavelength coverage
• 3400 - 8500 gt 3200 - 9000
• Decrease field flattener to 8 mm (crystal
  availability)
• Optimize merit function
• Put 625 mm length constraint on camera
• Remove 3 elements (including one entire doublet)
  from camera
• Images
• Mean 0.25 arcsec
• Worst 0.4 arcsec ( 10 worse fix this)

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PFIS Optical Design
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PFIS Image Quality
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Image quality vs pupil and focal ratio

• DD SAC for
• F/4.6, D 10.5,11,11.5m
• F/3.85, D 11m
• Optimize PFIS for slit focus using SAC vignetting
• Add SAC aberrations

• Little net difference! Prefer larger pupils
• Smallest beam size at filters
• 11m
• F/3.85
• Summary
• How about 11m, F/4.2

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Mechanisms and Control

• Mechanisms
• Slitmasks, filters, and gratings jukebox
  selectors
• 7 pneumatics, 8 steppers

• Software LabView/ Linux. Integrate mechanism
  and CCD control
• I/O "distributed" - commercial backplane control
  modules multiplexed to single ethernet or serial
  cable
• Power power management to allow multiplexing of
  motor controllers and minimize power dissipation

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PFIS Structure - Stiffness

• First attempt at modeling structure. Assume
• same specification as PFP payload mount point lt
  6 mm deflection
• this is delta over a ?6 deg tracker trajectory
• total weight (visible beam structure) lt 250 kg
• Feasible, but complex, and requires extensive use
  of composites (expensive). Mitigation
• relieve spec. Doing detailed optical sensitivity
  study
• look at alternate camera articulation geometry

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Configuration Articulation in-plane
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Configuration Articulation 45 deg
Visible beam
IR beam
Focal plane
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Design Tradeoffs

• Advantages of out-of-plane design
• Very little projection beyond focal plane
• More opportunity for truss cross-bracing
• Easier to incorporate two beams
• More room for collimator mechanisms
• Disadvantages
• Larger envelope
• Harder to draw and model

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Budget Status

• Detailed budget (definition phase task) not
  complete
• Funds required to complete definition study and
  to encumber salaries for start of preliminary
  design
• Propose definition phase and preliminary design
• Statement of work
• Schedule
• Budget
• Seek approval of UW in-kind contribution,
  possibly contingent on progress at March '01
  Board meeting
• Through March '01 CY179K
• Through PDR CY367K
• cf concept proposal through PDR 98350K 01382

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Statement of Work Preliminary Design

• General Tradeoff studies to establish baseline
  design and specifications, culminating in
  Preliminary Design Review at Sept SALT meeting in
  Madison
• Interface Complete PFP interface requirements
• Mechanical
• Tradeoff alternative truss structure designs
• Establish baseline mechanism designs
• Optical
• Optical design tradeoffs vs science instrument
  requirements
• Perform optical sensitivity analysis to establish
  optical element specifications
• Control Establish baseline instrument control/
  software requirements
• Management Develop a more accurate cost
  estimate, with margins, for the comprehensive
  design and construction phases.
• Partners SAAO Detectors Rutgers
  Etalons/Mechanisms UNC VPH?

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Schedule