Adaptive Optics designs for an Infrared Multi-Object Spectrograph on TMT

The Thirty Meter Telescope (TMT), the next generation giant segmented mirror telescope, will have unprecedented astronomical science capability. Since science productivity is greatly enhanced through the use of adaptive optics, the TMT science team has decided that adaptive optics should be implanted on all the IR instruments. We present the results of a feasibility study for the adaptive optics systems on the infrared multi-object spectrograph, IRMOS and report on the design concepts and architectural options. The IRMOS instrument is intended to produce integral field spectra of up to 20 objects distributed over a 5 arcminute field of regard. The IRMOS adaptive optics design is unique in that it will use multiple laser guidestars to reconstruct the atmospheric volume tomographically, then apply AO correction for each science direction independently. Such a scheme is made technically feasible and cost effective through the use of micro-electromechanical system (MEMS) deformable mirrors.