Surface-Micromachined Optical Interferometry System Utilizing Three-Dimensional Micromirrors and Microgratings

This paper presents a novel micro-optical interferometer incorporating three-dimensional micromirrors and microgratings. The interferometry system comprises a fixed grating mirror, two rotatable reflection mirrors, and a movable grating mirror driven by an electrostatically actuated oscillating structure. The use of a curved polysilicon structure lowers the electrostatic operating voltage (4 V) of the oscillating structure substantially and permits high-speed movement (2 kHz) of the grating. The novel system presented in this study provides a wider modulation frequency, and hence a wider frequency response. Furthermore, the proposed micro-optical interferometer can be applied to a micro-optical bench to facilitate signal modulation and precision measurement applications.