Citation:
Helen D. Ford and Ralph P. Tatam. Coherent fibre bundles, imaging bundles, OCT, optical fibre sensing. Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIII, March 2009,
edited by James G. Fujimoto, Joseph A. Izatt, Valery V. Tuchin, Proc. of SPIE Vol. 7168, 71682P
Abstract:
Endoscopic OCT probes deliver light to the measurement region via a single
optical fibre mounted in a probe head. The output beam is focused onto the
sample, providing a single point measurement. The beam is translated, using
mechanical scanning at the probe tip, to address a line or area of sampling
points and produce an image. We are investigating a swept-source OCT system
incorporating coherent fibre bundles, to allow many measurement points to be
addressed, within an area of the sample, without the need for mechanical motion
within the endoscope probe. Scanning components are still present at the input
of our system, but are no longer required within the flexible ndoscope section.
This allows a small-diameter, electrically passive probe to be engineered using
off-the-shelf scanning components. A common-path probe design is proposed, in
which the bundle is external to the OCT interferometer. This eliminates contrast
variations caused by non-controllable differences in the state of polarisation
between fibres. Imaging bundle fibres are typically few-moded, which can lead to
ghost features and reduced SNR in OCT images, but the common-path configuration
also removes cross-mode interference problems, and reduces dispersion artefacts.
OCT images of a microscope cover-slip and a sample of spring onion, acquired
using the swept-source, bundle-based OCT system are presented. Features peculiar
to the inclusion of the fibre bundle are discussed, and directions for future
development of the system are outlined.
