Static and dynamic micro deformable mirror characterization by phase-shifting and time-averaged interferometry

摘要

Since micro deformable mirrors based on Micro-Opto-Electronico-Mechanical Systems (MOEMS) technology would be essential in next generation adaptive optics system, we are designing, realizing, characterizing and modeling this key-component. Actuators and a continuous-membrane micro deformable mirror (3*3 actuators, 600*600 μm~2) have been designed in-house and processed by surface micromachining in the Cronos foundry. A dedicated characterization bench has been developed for the complete analysis. This Twyman-Green interferometer allows high in-plane resolution (4μm) or large field of view (40mm). Out-of-plane measurements are performed with phase-shifting interferometry showing highly repeatable results (standard deviation < 5nm). Features such as optical quality or electromechanical behavior are extracted from these high precision three-dimensional component maps and FEM can be fitted. Dynamic analysis like vibration mode and cut-off frequency is realized with time-averaged interferometer. The deformable mirror exhibit a 350 nm stroke for 35 volts on the central actuator. This limited stroke could be overcome by changing the components material and promising actuators are made with polymers.