Frontside-only processing of 2-D MEMS scanner for miniature dual-axis confocal microendoscopes

We present a 2-D MEMS scanner for 3.2mm-diameter dual-axis confocal microendoscopes, which is fabricated by only front-side processing. Frontside-only processing greatly simplifies the process and reduces the cost of the fabrication. Furthermore, by removing the conventional backside etch window, the process enables solid, compact, and robust chip designs that significantly eases handling and packaging. To achieve 2-D imaging in dual-axis confocal microscopy, our scanner is gimbaled, but the outer frame of the gimbal is removed in order to minimize the size of the scanner chip. In static operation, the scanner has optical deflection angles of ~±5.5° at 190V and ±3.8° at 100V for the outer and inner axes, respectively. At the torsional resonances, the optical deflection increases to ±11.8° at 1.18kHz for the outer axis and ± 8.8° at 2.76kHz for the inner axis, when the mirror is driven by (62 + 37sinωt)V and (68 + 37sinωt)V, respectively.