The Prime Focus Imaging Spectrograph Design and Capabilities Eric B. Burgh SALT/PFIS Instrument Scientist

The Prime Focus Imaging Spectrograph First generation, all-purpose spectrograph for SALT Optical Imaging Spectroscopy and Spectropolarimetry 320 – 900 nm. All-refractive collimator and camera using crystals for UV throughput Upgrade capability for infrared camera Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Optics Layout F/4.2 collimator, 150 mm diameter (fold mirror not shown) Volume Phase Holographic gratings Lead to need for articulating camera F/2.2 camera, first element asphere Articulates up to 100 degrees (VPH grating a=50 deg in Littrow) Polarimetric Optics ¼ and ½ waveplates, Wollaston beamsplitter Double-etalon Fabry-Perot system Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Design Highlights Weight/space constraints Accessibility Wavelength coverage: Crystals (CaF2 and NaCl) Anti-reflection coatings (0.5% reflections) High UV Quantum Efficiency CCDs (Marconi) Multiple configurations: Complex mechanisms/interfaces Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Grating Server Collimator Optics Camera Detector Dewar Slit Mask Server Waveplate Mechanism Filter Server Articulation Rail Open Truss Structure Science with SALT – Cape Town 29 October 2003 Fabry-Perot Etalons

The Prime Focus Imaging Spectrograph Grating Mechanism Collimator Optics Fold Mirror Detector Shutter Slit Mask Server Science with SALT – Cape Town 29 October 2003 Filter Mechanism

The Prime Focus Imaging Spectrograph Camera Focus Articulation Slit Mask Server Etalon Inserters Wave Plate Mechanism Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Expected Performance Expected system throughput of “fixed” optics. Includes anti-reflection coatings and fold mirror reflectivity. Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Expected Performance Measured CCD efficiency for PFIS mosaic chips. Chips will be arranged to take advantage of the high QE of Chip SALT-03 at “blue” end of mosaic. Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Grating Complement Grating Complement (5 VPH gratings and one standard surface relief transmission grating) Grating Wavelength Coverage Usable Angles (degrees) Bandpass per tilt (nm) Resolving Power (1.25 arcsec slit) SR300 390—900 nm 390/440 250—600 G0900 320—900 nm 12—20 ~300 600—2000 G1300 19—32 ~200 1000—3200 G1800 450—900 nm 28—50 150—100 2000—5500 G2300 380—700 nm 30—50 100—80 2200—5500 G3000 320—540 nm 32—50 80—60 Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph VPH Grating Performance VPH gratings have tunable blaze. Best efficiency when used near Littrow (a=b) Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph VPH Grating Performance VPH grating complement superblaze curves. Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph VPH Grating Performance Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Double-Etalon Fabry-Perot System Double-etalon system isolates high-resolution, narrow bandpass. High- and low-resolution modes: R=500—12500 Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Current Status: Optics: virtually all elements fabricated (some coated) Mechanisms: Slit mask completed and wired, waveplate almost completed Science with SALT – Cape Town 29 October 2003

The Prime Focus Imaging Spectrograph Upcoming Schedule Milestones Structure fabrication (Rutgers) Jan 2004 Optomechanical assembly  Feb 2004 Integration and testing  thru Aug 2004 Commissioning  begin Sep 2004 Relevant web pages: Observer’s guide v1.0 – http://www.sal.wisc.edu/~ebb/pfis/observer/ VPH Spectroscopy simulator – http://www.sal.wisc.edu/~ebb/pfis/observer/specsim.html PFIS photos – http://www.sal.wisc.edu/~ebb/pfis/pics/ Science with SALT – Cape Town 29 October 2003