Tests on micro-mirror arrays for adaptive optics

Micro Mirror Arrays (MMAs) offer the potential of a high spatial and temporal resolution technology for wave-front control applications. In this paper a new Micro-Electro-Mechanical-System (MEMS) based MMA type is investigated. As opposed to most other MMA technologies which involve flip mirrors with only two possible orientations, this system can support two different mirror designs, piston-type mirrors for a continuous phase adjustment and tilt mirrors for light discarding purposes. The MMA's wavefront correction capabilities are being investigated in a breadboard which simulates continuous distortions and step errors, such as those that could be expected from lightweight primary mirrors of space telescopes or segmented mirrors, respectively. The wavefront is corrected by the MMA, then coupled into a monomode fiber. Four different correction methods have been tested, two stochastic approaches, a closed-loop Shack-Hartmann approach and an interferometric approach. Comparison of coupling efficiency is made between these approaches and against theoretical calculations.