This paper investigates the use of a PMN-PT [001] piezoelectric actuator to be integrated in smart Micro-Opto-Electrical-Mechanicals Systems (MOEMS). Unlike most piezoelectric materials, PMN-PT [001] can generate large-stroke out-of-plane displacement. This is due to its very high longitudinal piezoelectric coefficient of up to 4500pm/V. After an introduction on MOEMS actuation and a short description of the Reconfigurable Free Space Micro-Optical Bench (RFS-MoB) in which the studied actuator may be included is presented, a bulk actuator is proposed. FEM simulations are then presented highlighting some tradeoffs: increased displacement with the reduction in size while decreasing the optical aberration. It was observed that for actuators with a smaller surface than 800x800µm 2 and 200µm thick, displacement larger than 325nm is largely achievable and that the size of the usable area of the actuator varies in size with the applied voltage. I.