A design methodology for a bulk-micromachined two-dimensional electrostatic torsion micromirror

This paper presents a design methodology for a two-dimensional (2-D) electrostatic torsion micromirror fabricated with bulk-micromachining technology. The theoretical models in mechanical and electrostatic fields presented here provide insights into the influences of different design parameters on micromirror performance. Parametric numerical models built in ANSYS are used to more accurately predict its performance and further refine the design parameter values derived from the theoretical models. By use of the electrical analogy method, an equivalent electrical circuit is built in PSPICE to predict the static and dynamic performance of this micromirror, with the numerical simulation results as the input parameters. The equivalent electrical circuit has been demonstrated to be a simple and powerful approach to characterize the performance of this 2-D torsion micromirror. The test results for this micromirror reveal very good agreement between experimental and numerical results, taking into account fabrication tolerances and experimental accuracies. Incorporating the fabrication tolerances of bulk-micromachining technology, this design methodology can be readily applied to performance characterization and design optimization.