A 2-axis optical scanner driven nonresonantly by electromagnetic force for OCT imaging

Abstract

This paper presents a 2-axis optical scanner fabricated by a MEMS process for use in optical coherence tomography (OCT) imaging. It comprises planar coils placed above a single permanent magnet; it is driven by an electromagnetic force in the static or low frequency (∼10 Hz) mode, which is required for OCT systems. Two coils are fabricated on a movable plate for X-axis rotation with a mirror, and four coils are fabricated on a movable frame for Y-axis rotation; each coil has a double-layer structure. Two types of torsion beams are designed and tested. The maximum optical scanning angle of the optical scanner with meandering torsion beams was ±8° for a drive current of ±4.6 mA and ±10.3 mA in the X- and Y-axes, respectively. The resonant frequencies of the optical scanner were 106 Hz and 80.5 Hz in the X- and Y-axes, respectively; the frequency characteristics indicated that the scanner can be driven from dc to several Hz. The fabricated optical scanner was applied to an OCT system and cross-sectional images of an onion were obtained by scanning along both axes.