Articoli Scientifici di Oftalmologia
Argomento : 32
μOCT imaging using depth of focus extension by self-imaging wavefront division in a commonpath fiber optic probe
Abstract: Optical coherence tomography (OCT) is an attractive medical
modality due to its ability to acquire high-resolution, cross-sectional images
inside the body using flexible, small-diameter, scanning fiber optic probes.
Conventional, cross-sectional OCT imaging technologies have
approximately 10-μm axial resolution and 30-μm lateral resolution,
specifications that enable the visualization of microscopic architectural
morphology. While this resolution is useful for many clinical applications,
it is insufficient for resolving individual cells that characterize many
diseases. To address this gap, a supercontinuum-laser-based, μm-resolution
OCT (μOCT) system and a 500 μm-diameter, extended depth of focus
single fiber optic probe for endoscopic and intravascular imaging were
designed and fabricated. At the distal tip of the fiber optic probe, a
cylindrical waveguide was used to divide the wavefront to provide multiple
circular propagation modes. Once transmitted through a relatively high NA
lens (NA >0.1), these modes were projected as multiple coaxial foci (~3 μm
full width at half maximum (FWHM)) over a greatly extended focal depth
range. The distal tip of the probe also contained a common-path reference
reflectance to minimize polarization and dispersion imbalances between
sample and reference arm light. Measurements showed that the probe
provides a 20-fold depth of focus extension, maintaining a 3-5 µm lateral
resolution (FWHM of PSF) and a 2 μm axial resolution over a depth range
of approximately 1 mm. These results suggest that this new optical
configuration will be useful for achieving high-resolution, cross-sectional
OCT imaging in catheter/endoscope-based medical imaging devices.
©2016 Optical Society of
America
OCIS codes: (050.1220) Apertures; (070.7345) Wave propagation; (080.2740) Geometric
optical design; (120.4640) Optical instruments; (170.2150) Endoscopic imaging; (170.4500)
Optical coherence tomography.