Forward-Imaging Swept Source Optical Coherence Tomography using Silicon MEMS Scanner for High-Speed 3-D Volumetric Imaging

We demonstrate a fiber-based forward-imaging swept source OCT (SS-OCT) system using a two-axis silicon micromachined vertical comb-drive microscanner for high-speed, 3-D imaging of biological specimens. Higher signal-to-noise ratio of SS-OCT over traditional time-domain techniques, combined with low beam-steering loss of silver-coated scanning micromirrors with over 90% reflectivity, provide good imaging performance. Fast wavelength scanning of the laser source (scan rate: 20 kHz) over 110 nm spectral bandwidth enabled image acquisition at 8 million voxels/sec (3-D imaging) or 40 fps (2-D imaging, 500 transverse pixels per image). We successfully acquired en face and tomographic in vitro images of rigid structures (microscanner), soft materials (onion and pickle slices), and in vivo images of epidermis. Lateral resolution of 12.5 mum and axial resolution of 10 mum over a 2x1times4 mm³ imaging volume has been demonstrated. The compact forward-imaging OCT probe may be suitable for image-guided minimal-invasive examination of various diseased tissues.