Prime Focus Imaging Spectrograph Status

1
Prime Focus Imaging SpectrographStatus

• Engineering Status
• Optics
• Mechanical
• Control System
• Management
• Budget
• Schedule

2
Optics

• Design Updates
• Slit Throughput
• VPH Grating Complement
• Optomechanical
• Concerns
• Procurement plan

3
Optics Design

• Updated camera and collimator to final indices
• 20 image quality degradation
• decrease manufacturing margin?
• relieve spec?
• Completed thermal design. Focus in camera
• Updated pupil placement and fold mirror position
  for maximum NIR collimated beam
• Fused silica -gt fused quartz in common collimator
  beam (for NIR)
• Camera configuration update

Details
Details
Details
4
Slit Throughput

• PDR max resolution 6250 overstated. Used
  median seeing 0.9 arcsec, not telescope image
• Model using seeing degraded to 37 deg ZD, actual
  SAC, actual PFIS model
• In median seeing, a 1.25 arcsec slit will give
  70 throughput
• Resolution at a given grating angle reduced to
  70.
• Found can increase maximum articulation of camera
  to 100 deg, increases max resolution 20 R
  5500 at 50 deg tilt, 1.25 arcsec slit

5
Spectral Resolution vs. Throughput
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VPH Grating Complement

• VPH procurement in next 6 months, tradeoff
  required UV efficiency vs high resolution
  efficiency
• Suggest efficiency in UV for highest and lowest
  density gratings efficiency at high resolution
  for other three
• Note that SALT can easily add VPH gratings-
  magazine designed for swapout

7
VPH tradeoff
8
Optomechanical

• Largest PDR risk optics, especially
  optomechanical, underbudgeted
• Award subcontract for optomechanical to J. Alan
  Schier
• optomechanics for Keck ESI, DEIMOS
• comfortable with fluid coupling, salt, solgel
• Tasks
• mounting tolerancing
• design, fabricate lens holders
• assemble lens groups

9
Current concerns

• Coating strategy
• baseline solgel on interior surfaces hard
  elsewhere
• cost poorly defined
• Stress birefringence in collimator potentially
  degrading polarimetric efficiency
• blanks NaCl possible problem lack of data
• 4 CaF2 blank costs may be increased
• investigating VPH and etalon effects

Details
10
Optics procurement

• before CDR
• third etalon (before years end to get good
  price)
• fold flat/ coating
• camera/ collimator blanks
• grating blanks
• just after CDR
• camera/ collimator figuring
• waveplates, beamsplitter
• VPH gratings

11
Structure/ Mechanisms

• Structure
• guide mount interface designed
• collimator assembly
• Mechanisms designed
• waveplate
• slitmask
• grating. 6 grating complement
• camera articulation.
• Will do full articulation in lt 20 sec (enable
  PFIS imaging mode as slitmask setup)
• Articulate to 100 deg

Details
12
Control System

• Hardware
• generic mechanism test bed operational use for
  LabView learning curve, answering operational
  questions for mechanism designs
• wiring architecture box placement cable harness
• Software
• actually operating hardware
• prototype client / server, scripting developed
• consistent with telescope architecture

Details
13
Management

• Budget re-projection
• Schedule

14
Cost-to-Completion Deltas

• Base Dollars

15
Chief Deltas

• Q1-2 (94K)
• CDR electrical engineering underestimate 15K
• SAAO Cryotiger, etc 25K
• US slowed inflation 50K
• Q2-2 (139K)
• Drafting subcontract underestimate 97K - 50K -
  20K 27K. Control mech design schedule risk.
• Optomechanical subcontract 220K - 50K - 20K
  150K. Control optics technical/ schedule risk
  biggest PDR budget deficiency

16
Prognosis

• Contingency use (58) somewhat above expected
  (50) at this point, but still on track.
  Remaining deltas will be much better known at
  CDR
• Capital purchases. Preliminary RFQs on largest
• likely increases CaF2 blanks coatings
• likely savings mechanisms/controls lens
  fabrication slitmask mill
• Schedule. Remaining contingency would cover 8
  months slip.
• When do we start spending contingency? At current
  rate, Q1 04 at rate which would spend cap, Q4
  03 (well after CDR)

17
Schedule

• Milestone CDR 17 Mar, 2002
• slipped 2 months from PDR mechanical design
  critical path
• recover drafting/ engineering subcontract help
• Optical
• optomechanical subcontract kickoff
• procure blanks, issue pre-CDR RFQs
• Mechanical 4 most complex mechanisms completed
• Control System in progress
• hardware wiring diagram
• Labview design well under way
• Detail fabrication/ testing schedule in work this
  month

Details
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Done!
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Optics Details
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NIR Beam
21
Optics Configuration
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Camera

• triplet modification
• CaF2 -gt silica
• aplanatic configuration
• reduced MAD on asphere
• focus singlet triplet

23
Birefringence Budget

• Unusual SALT configuration puts large glass path
  (17 cm!) between waveplate and beamsplitter
• Stress birefringence at 45 to polarimetric axis
  causes depolarization d (p w)2 (w biref in
  waves). d lt 2 gt w lt 1/20 wave, biref/cm lt
  2-10nm/cm
• Have birefringence budget for
• Fused silica, quartz 1 -5 nm/cm
• CaF2 1-2 available at extra cost
• NaCl unknown. sample now being measured
• Folding flat LLNL coating
• VPH grating
• Etalon

24
Mechanical Details
25
Completed Designs
gratings
slitmask
collimator assembly
camera articulation
waveplates
26
Camera Articulation
camera tube
gearbox/ motor
pinion
pneumatic detent, 0.5 deg spacing
bearing
27
Camera Support
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Grating Mechanism
pneumatic insertor
linear stage selector
6 gratings
grating rotator
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Collimator Assembly
main collimator group
slitmask magazine
guider feet
waveplates
30
Waveplate Mechanism
halfwave plate
quarterwave plate
blank
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Slitmask Mechanism - 1
linear stage selector
magazine
pneumatic insertor
mask in position
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Slitmask Mechanism - 2
pneumatic extractor
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Control System Details
34
Generic Mechanism

• Test Hardware
• candidate motor, encoders, hall sensors,
  pneumatic
• motor drivers
• signal conditioner
• PXI motor card, I/O card

35
LabView

• Hierarchical VIs
• Commandable from scripts

36
Management Details
37
Detail CDR Schedule