Optical coherence tomography for endoscopes, using imaging fibre bundles and a conical mirror

Abstract

ABSTRACT Imaging fibre bundles and a conical mirror have been used to construct a passive, endoscopic OCT probe with no scanning components at the probe tip. Circular scanning of the beam projected onto the proximal face of the imaging bundle results in a corresponding circular scan at the distal end of the probe. A 45 o base-angle conical mirror turns the output light to produce a radially-directed beam that permits circumferential OCT scanning in quasi-cylindrical ducts. Keywords: Optical coherence tomography, OCT, conical mirror, imaging fibre bundles 1. INTRODUCTION Endoscopic optical coherence tomography (OCT) systems using imaging fibre bundles have been previously reported 1-5 . Incorporating imaging bundles into an OCT endoscope enables a 2-D region of the sample to be imaged, as light can be coupled sequentially into multiple fibre cores within the bundle, removing the need for miniaturised scanning components at the probe tip. The technique is compatible with both time-domain (TD-OCT) and swept-source (SS-OCT) systems. Imaging is achieved by coupling light in rapid succession into each element of a straight or curved row of bundle cores. Samples can be positioned either on-axis, with the sample surface normal to the system axis, or to one side of the probe tip, with the sample surface parallel to the optical axis and a turning mirror used to rotate the beam through 90