Most cancers occur inside human body, so endoscopic high-resolution imaging modalities are required for early cancer
detection and surgical removal. This paper reports in vivo endoscopic 3D imaging based on optical coherence
tomography (OCT). Endoscopic imaging is enabled by integrating rapid-scanning MEMS mirror into a miniature
imaging probe. The MEMS mirror has an aperture size of 1 mm by 1 mm and a chip size of 2 mm by 2 mm. The optical
scan angle exceeds ±25 V at 6 Vdc, and thus large, constant-velocity, linear scan can be realized. The outer diameter of
the probe is only 5 mm. The axial resolution is about 10 μm and the imaging speed is 2.5 frames per second. Doppler
OCT imaging has also been demonstrated.
We report the design, fabrication, and measurements of a dual-reflective, single-crystal silicon-based micromirror that can perform circumferential scanning for endoscopic optical coherence tomography (EOCT). Full 360-deg optical scan angle (OSA) can be achieved by using a dual-reflective mirror with ±45-deg (or 90-deg) mechanical scan angle (MSA), where each reflective mirror surface contributes a 180-deg optical scanning. A novel surface- and bulk-combined micromachining process based on silicon on insulator (SOI) wafers is developed for fabricating the dual-reflective micromirror. The mirror flatness is maintained by the single-crystal-silicon device layer of SOI wafers, and aluminum is coated on both sides for reflection. A fabricated device demonstrated about half circumferential scanning range at resonance of 425 Hz. Other measured data include the radii of curvature, −129 mm (front surface) and 132 mm (back surface), and the reflectance, 86.3% (front surface) and 84.2% (back surface). This micromirror has the potential to realize full-circumferential-scanning EOCT imaging.
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).