The Prime Focus Imaging Spectrograph Design and Capabilities

1. The Prime Focus Imaging SpectrographDesign and Capabilities Eric B. Burgh SALT/PFIS Instrument Scientist

2. 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

3. The Prime Focus Imaging SpectrographOptics 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

4. The Prime Focus Imaging SpectrographDesign Highlights • Prime Focus: • 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

5. 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

6. 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

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

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

9. The Prime Focus Imaging SpectrographExpected 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

10. The Prime Focus Imaging SpectrographGrating Complement • Grating Complement (5 VPH gratings and one standard surface relief transmission grating) Science with SALT – Cape Town 29 October 2003

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

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

13. The Prime Focus Imaging SpectrographVPH Grating Performance Science with SALT – Cape Town 29 October 2003

14. The Prime Focus Imaging SpectrographDouble-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

15. The Prime Focus Imaging SpectrographCurrent 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

16. The Prime Focus Imaging SpectrographUpcoming 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