Design of a piezoelectric mirror scanning device using topology optimization

1. Abstract There are several optical applications in which a mirror or lens requires accurate manipulation, for example in microscanning or focusing optical systems. Typically, such devices are designed on a trial-and-error basis. To improve on this procedure, we apply topology optimization in the design of a piezoelectric micropositioner. The mechanism employs two piezoelectric stack actuators to provide the input displacement in a push-pull configuration. A compliant mechanism is used to amplify the input displacement. We investigate various objective and constraint functions, including simply maximizing output rotation, as well as maximizing stiffness subject to a required rotation being maintained. Furthermore, we propose the use of elements with drilling degrees of freedom in the topology optimization procedure. At WCSMO5, we demonstrated some of the salient features of elastic elements with in-plane rotations, or drilling degrees of freedom (dof’s). We have since developed very accurate and robust piezoelectric finite elements with drilling dof’s. The use of planar (elastic and piezoelectric) elements with rotational degrees of freedom permits their connection to beam elements. We exploit this feature in proposing a method to suppress or interpret, undesirable material layouts (such as checkerboards, one node hinges and diagonal members). These configurations, locally, all have a nonmonotonic density distribution around specific nodes. In our scheme, we model these material configurations using beam elements, while retaining 2-D planar elements in the remainder of the model. 2.