Analytical and experimental modal analysis of a silicon microstructure

Numerical and experimental dynamic modeling techniques for microstructures are currently the subject of intensive research. In this work, the dynamic characterization of a monolithic, single-crystal silicon scanning mirror for laser applications is investigated. It consists of a rigid plate suspended by one or two torsion bars. Numerical modeling of the scanning mirror, using the Finite Element method, is described. An experimental modal analysis of the first two modes is performed. The non-intrusive excitation mechanism and the optical measurement techniques used in the experiments are discussed. The dynamic responses of the microstructures are measured with a laser Dopplervibrometer. An algorithm based uponChebycheff orthogonal polynomials is used to estimate the modal parameters. A high quality factor is identified. Good agreement was found between numerically predicted and experimentally identified modal parameters.