This paper reports the design, fabrication and measurements of a dual-reflective, single-crystal silicon based micromirror
that can perform full circumferential scanning (FCS) for endoscopic optical coherence tomography (EOCT). In the
proposed FCS-EOCT probe, two optical fibers are used to deliver light beams to either surface of the micromirror, which
can rotate ±45° (or 90°) and thus a 180° optical scanning is obtained from each mirror surface, resulting in full
circumferential scans. A novel surface- and bulk-combined micromachining process based on SOI wafers is developed
for fabricating the dual reflective micromirror. The single-crystal-silicon device layer of SOI wafers is used for mirror
flatness, and Al is coated on both sides for high reflectivity. With one light beam delivered to each mirror surface, full
360° scans have been observed. Other measured data include the resonant frequency: 328Hz, radius of curvatures: - 124 mm (front surface) and 127 mm (back surface), and the reflectances: 81.3% (front surface) and 79.0% (back surface).
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