Integrated Near-Infrared Dual-Modality Imaging With Common Path Fiber Optic System

A simple configuration of combining two imaging modalities for diagnostic endoscopy is experimentally demonstrated. It is based on a near-infrared optical imaging system by using a common fiber optic path, where the probing arm provides both the sample and the reference paths. This feature allows integrating the optical coherence tomography and the confocal optical microscopy with simply inserting a directional optical coupler at the receiver's measurement part. The coupler divides the two different imaging modalities for separately measuring optical signals from the specimen without employing additional instrumentation except for a 3-dB loss of received power in return. Furthermore, the acquired tomography signal is related to the confocal point spread function of the scanning optical probe in the imaging system. As a result, the surface and cross-sectional images of a biological tissue (kidney with a tumor) sample were successfully obtained and registered using the proposed combined imaging scheme incorporating different measurement systems.