1. Mechanical Changes Required Due to Proposed IRMS Rx V2 R. Weber September 27, 2011

2. Windows & CSU No changes required for window mounts Because of the flip in curvature of the focal surface, the CSU supports will need to be shortened by ~4 mm so that the focus is at the incoming edge of the central masking bar, rather than the exiting edge. Or, the instrument could be positioned ~4 mm further from NFIRAOS. TMT focus (blue arc) Keck focus (ends of ray pencils) Masking bar thickness 9/8/20112

3. Field Lens Girdle thickness increased from 11.5 to 12.9 mm- better for bonding Center of girdle shifted 2.694 mm towards CSU- lens mount flexure pockets machined deeper in cell 9/8/20113 MOSFIRE (solid)IRMS (transparent)

4. Collimator Barrel Girdle center shifts: Col #2= -0.5 mm, Col #3= 2.7 mm, Col #4= 1.6 mm, Col #5= 0.03 mm, Col #6= - 0.05 mm. These relatively small shifts in the lens girdle centers should be achievable through a combination of cell spacer shim alterations and/or altering mount flexure pocket depths. Girdle widths are all comparable or slightly larger than MOSFIRE design- no bonding issues. 9/8/20114 MOSFIRE lenses (solid) IRMS lenses (transparent)

5. Camera Barrel: (Cells #1-#4) Cell #1: girdle center shifts -2.0 mm and girdle thickness increases by 0.8 mm to 12.0 mm; minor cell spacer shim modifications required. Cell #2: girdle center shifts -1.6 mm and girdle thickness remains the same; minor cell spacer shim modifications required. Cell #3: girdle center shifts -1.9 mm and girdle thickness decreases by 0.7 mm to 52.7 mm; minor cell spacer shim modifications required. Cell #4: girdle center shifts -1.9 mm and girdle thickness increases by 0.6 mm to 11.1 mm; minor cell spacer shim modifications required. 9/8/20115 MOSFIRE lenses (solid) IRMS lenses (transparent)

6. Camera Barrel: (Cells #5, #6, & Field Flattener/Detector) Cell #5: girdle center shifts - 0.8 mm and girdle thickness increases by 1.8 mm to 9.9 mm; minor cell spacer shim modifications required. Cell #6: girdle center shifts - 1.4 mm and girdle thickness decreases by 2.2 mm to 26.3 mm; minor cell spacer shim modifications required. Field flattener/detector: girdle center shifts -1.2 mm and girdle thickness increases by 0.6 mm to 9.9 mm; minor cell spacer shim modifications required. 9/8/20116 IRMS focal surface MOSFIRE lenses (solid) IRMS lenses (transparent)