Response of magnetic fluid deformable mirror with large stroke surface deflection

Zh. Wu - Sh. Yuan - Sh. Xie - L. Min - M. Huang

Department of Precision Mechanical Engineering, Shanghai University, Shanghai 200072, China

Abstract
The stroke of the current wave front corrector, i.e. solid deformable mirrors, is small and far from enough to meet the requirement of large aberration corrections. In this paper, a magnetic fluid (ferrofluid) based deformable mirror which can supply a large stroke surface deflection is presented. By superposing a large uniform magnetic field to the small perturbed magnetic field generated by the underneath miniature electromagnetic coils, the proposed deformable mirror can supply a large stroke more than 100 μm. An analytical surface dynamic model of mirror is developed, and the linearity of the surface response to the input current of the electromagnetic coil is analyzed using COMSOL Multiphysics combined with MATLAB software. In addition, the response characters of the surface deflection of the deformable mirror within a large stroke range are verified experimentally based on a designed prototype magnetic fluid deformable mirror. Tables 5, Figs 13, Refs 14.