The Prime Focus Imaging Spectrograph Design and Capabilities

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 • Prime Focus: – Weight/space constraints – Accessibility • Wavelength coverage: – Crystals (Ca. F 2 and Na. Cl) – 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 Science with SALT – Cape Town Fabry-Perot Etalons 29 October 2003 Open Truss Structure

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

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 antireflection 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 SR 300 390— 900 nm G 0900 320— 900 nm G 1300 Usable Angles (degrees) Bandpass per tilt (nm) Resolving Power (1. 25 arcsec slit) 390/440 250— 600 12— 20 ~300 600— 2000 390— 900 nm 19— 32 ~200 1000— 3200 G 1800 450— 900 nm 28— 50 150— 100 2000— 5500 G 2300 380— 700 nm 30— 50 100— 80 2200— 5500 G 3000 320— 540 nm 32— 50 80— 60 2200— 5500 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 highresolution, narrow bandpass. • High- and lowresolution 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 v 1. 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