1. 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. 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. 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 IRMS- Imaging Mode FieldRMS spot diameter Radiusarc-secpixels 00.0791.27 0.71'0.0951.52 1'0.1141.82

4. 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. 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 IRMS - Spectroscopic Mode Enslit Energy in 2x2 pixels Y- band J- band H- bandK-band avg84%83%81%82% max100%95%97%100% min71%70%50%40% Half-Width (in microns) for 80% enslit energy Y- band J- band H- bandK-band avg16171817 max24 3328 min91112 Width ( in pixels ) for 80% enslit energy Y- band J- band H- bandK-band avg1.8 2.01.9 max2.6 3.63.1 min1.01.21.3

6. 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.