Prime Focus Imaging Spectrograph

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Prime Focus Imaging Spectrograph (PFIS)
SALT combined with SAC provides 11m telescope
pupil at F/4.2 and FOV 8 PFIS optical design
includes

• All-refractive collimator camera
• coverage 3200-9000 Å
• (future upgrade 8500 Å 1.7 µm)
• beam size 150 mm
• images of lt0.30 over the full range
• for a reduced 0.5 slit resolution up to
• R12000
• articulated camera for tuning of Volume
• Phase Holographic (VPH) grating efficiency

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Mechanical design
PFIS
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Optical design
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PFIS detector

• mosaic of three Marconi/EEV 42-80
• (2048x4096 15µ pixels)
• total of 6144x4096 pixels
• (95x61 mm)
• for a F/2.2 camera

• the pixels are 0.13
• a 0.9 seeing disk is critically sampled for
• 2x2 binning
• a 0.5 slit is critically sampled for unbinned
• readout

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Readout Modes and Times
Normal readouts 4096x6044 pixels in 3.6 s with
5e- read noise Frame Transfer 2048x6044 pixels
in 1.8 s with 5e- read noise
High Time Resolution
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Spectral Resolution vs. Throughput
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Signal-to-noise vs. Magnitude
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Predicted sensitivity as compared to
slit spectrographs on other telescopes
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Volume Phase Holographic Spectroscopy
Wavelength Coverage Spectral Resolution
Contours at 90, 70, 50 efficiency. Assumes
1.25 slit, amax45 deg
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Fabry-Perot Imaging Spectroscopy
Low resolution (R500-1000) uses a single
etalon and interference filters Medium (R2500)
and High (R12500) resolution use two etalons
in series
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Polarimetry

• Linear polarimetry
• ½ wave plate, 8 positions
• Imaging polarimetry, 4 FOV
• Longslit spectropolarimetry
• Time-resolved polarimetry or
• spectropolarimetry
• Circular polarimetry
• ½ wave plate (8 positions)
• ¼ wave plate (2 positions)
• Wolaston beamsplitter
• mosaic of 9 calcite prisms and splits
• the 45 polarisation states

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Imaging VPH Grating Spectropolarimetry
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Fabry-Perot Imaging Spectropolarimetry
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PFIS Niches
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Slit Spectrographs on larger telescopes
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PFIS Operational Modes
Forbidden modes
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