NGAO Instrumentation Cost Drivers and Cost Savings September 2008 Sean Adkins

2 What drives science instrument costs? All designs are relatively lean already Suspected cost drivers: –Technical difficulty d-IFS probe arm accuracy and stability Near-IR and Visible coronagraphs Visible IFU Internal wavefront error control for all instruments Calibration and alignment (pupil registration, etc.) –Pixel sampling and FOV (detector size) –Number of d-IFS channels

3 What can save cost? Keep the imagers simple –Resist the temptation to ask for more than one plate scale –Accept that imagers do not offer spectroscopy Accept higher static instrumental wavefront error –Design instrument to optimize performance of wfe measurement –Allocate some DM stroke to correcting static instrumental wfe –Incorporate some other correction technique? Evaluate the possibility of putting the coronagraph in the AO system –Hard to do for both wavelength ranges –Compounds the alignment difficulties – need imager to align coronagraph? ( may imply coronagraph belongs in instrument) –May not or won’t work for near-IR (needs to be cryogenic) Stripper imagers –Just detectors and filters –No coronagraphs –Keep telecentric ~ f/46.5 narrow field relay but eliminate field curvature –Must put Lyot stop in AO system, still has to be cold for near-IR

4 “Radical” Cost Saving Concept Standardized near-IR cryostat, camera, focal plane design used for both the near-IR imager and each d-IFS spectrograph channel Common MOAO relay design for TT and d-IFS w/ 32 x 32 MEMS Eliminate narrow field relay Incorporate 64 x 64 MEMS in each imager and locate at “wide” field relay/OSM plane –Eliminates dichroic changer –Include on instrument low order wavefront sensing Duplicate the narrow field MOAO relay (30" dia. FOV), but 32 x 32 MEMS for d-IFS, 3 d-IFS channels (post OSM) per MOAO relay instead of 1