Optomechanical design concept for GMACS: a wide-field multi-object moderate resolution optical spectrograph for the Giant Magellan Telescope (GMT)

摘要

We describe the conceptual optomechanical design for GMACS, a wide-field, multi-object, moderate-resolution opticalspectrograph for the Giant Magellan Telescope (GMT). GMACS is a candidate first-light instrument for the GMT andwill be one of several instruments housed in the Gregorian Instrument Rotator (GIR) located at the Gregorian focus. Theinstrument samples a 9 arcminute x 18 arcminute field of view providing two resolution modes (i.e, low resolution, R ~2000, and moderate resolution, R ~ 4000) over a 3700 Å to 10200 Å wavelength range. To minimize the size of theoptics, four fold mirrors at the GMT focal plane redirect the full field into four individual "arms", that each comprises adouble spectrograph with a red and blue channel. Hence, each arm samples a 4.5 arcminute x 9 arcminute field of view.The optical layout naturally leads to three separate optomechanical assemblies: a focal plane assembly, and two identicaloptics modules. The focal plane assembly contains the last element of the telescope's wide-field corrector, slit-mask,tent-mirror assembly, and slit-mask magazine. Each of the two optics modules supports two of the four instrument armsand houses the aft-optics (i.e. collimators, dichroics, gratings, and cameras). A grating exchange mechanism, andarticulated gratings and cameras facilitate multiple resolution modes. In this paper we describe the details of theGMACS optomechanical design, including the requirements and considerations leading to the design, mechanismdetails, optics mounts, and predicted flexure performance.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.