Large size MEMS scanning mirror with vertical comb drive for tunable optical filter

This paper presents the design, fabrication and characterization of a large size MEMS scanning mirror in application of tunable optical filter (TOF). In the design of scanning mirror, vertical comb drive is used for its large force density, low driving voltage and also no influence of pull-in effect. The mirror plate has a size of 2.7 mm x 1.8 mm which is suitable for the optical requirement of TOF. In each side of the mirror, 186 combs are set to provide a suitable rotation angle. The length, width and thickness of the combs are 300 mu m, 7 mu m and 25 mu m, respectively. The gap between the adjacent combs is 4 mu m. The scanning mirror with vertical comb drive has been successfully realized using the bulk micromachining technologies. The measured static and dynamic characteristics show that the scanning mirror can achieve a maximal rotation angle of 2.3 degrees with a direct current (DC) driving voltage of 95 V. The turn-on responding time of the scanning mirror is 1.887 ms and the turn-off responding time is 4.194 ms. The tuning function has also been demonstrated and a 1.507 ms tuning time between two adjacent channels is obtained. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.