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IRMS Preliminary results - overview

IRMS Preliminary results - overview. Optimize Field lenses in collimator and camera to for 1.39m field curvature on NFIRAOS Get good imaging performance Get marginal spectroscopy performance. Recommend collimator re-design to gain full performance. Pupil.

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IRMS Preliminary results - overview

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  1. IRMS Preliminary results - overview • Optimize Field lenses in collimator and camera to for 1.39m field curvature on NFIRAOS • Get good imaging performance • Get marginal spectroscopy performance. • Recommend collimator re-design to gain full performance.

  2. Pupil • Simple modification of field lens in collimator to match pupil to cold stop • Looks ok, some colour but with just changing field stop this is what you get. IRMS MOSFIRE

  3. Imaging • Modify field flattener in camera and field lens in collimator • Slightly worse, but within the original MOSFIE req. of over 0.97-2.45 microns with no re-focus. IRMS MOSFIRE

  4. Spectroscopy • In addition to collimator field lens and camera field flattener modification, allow for small refocus between spectral bands to improve image quality but image quality still worse than MOSFIRE. • about 82% enslit energy for design residual, so loss of spectral resolution occurs. IRMS MOSFIRE *Slit defocus not considered in calculation, calculation for an ideal ‘spherical’ slit mask

  5. Spectroscopy • MOSFIRE criteria was ensquared energy 80% within 2 pixels (pixels 18 microns ), and MOSFIRE achieve roughly 90% on average for design residual, leaving margin for manufacturing tolerances. • Need collimator redesign for new field curvature to regain full performance. Likely able to do this with lenses constrained to original lens groups ( a quick optimization was done which suggested this should be possible) *Slit defocus not considered in calculation, calculation for an ideal ‘spherical’ slit mask

  6. CSU – Configurable Slit Unit • Sag along slit height at slit mask in Keck is 4.17mm, and a 3 tiered arrangement of knife edges was used, for TMT, sag is ~50% more ( 6.4mm) so 5 tiered would probably be used • Sag along dispersion with keck was ~1mm, (@1.5’ )no correction for curvature on Keck, for TMT, will have ~1.6mm (@0.5’), so will have slit ‘blur’ for IRMS ( geometric blur of 24mas or 127nm RMS WFE for +/-0.8mm defocus). Slit losses at field edges will be marginal .

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