Design of the first-generation wavefront sensor and actuator geometry for the 6.5-m MMT adaptive optical system

A description is given for the geometry of the first generation adaptive-optical (AO) system being developed for the 6.5m single-mirror telescope that will replace the Multiple Mirror Telescope on Mt. Hopkins. The AO system consists of an adaptive secondary mirror with 330-actuators and a wave front senor composed of a 13 by 13 square subaperture array. The deformable mirror actuator vibrational modes were determined from a finite element model of the adaptive-secondary mirror. Numerical simulations in based on the finite element results were carried out to determine the expected performance of the system. Two reconstruction algorithms were compared - a least squares reconstructor and a modal equalization technique developed for this AO geometry. Strehl ratios are reported for the two algorithms for various guide star magnitudes and number of corrected wave front modes.

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