Reducing multipath artifacts of double-clad fiber in multimodal endoscopic optical coherence tomography

Abstract

Endoscopic multimodal optical coherence tomography (OCT) is an optical imaging technique that enables more accurate diagnosis of lesions in internal tubular structures by simultaneously acquiring morphological and biochemical information. A fiber optic rotary joint, which is a mechanically separated but optically connected part, based on a double-clad fiber (DCF) is employed to connect the system and the catheter. The core of the fiber transmits the OCT light, while the cladding transmits fluorescence. However, due to the use of DCF, OCT light transmitted through the cladding of the DCF may couple into the core of the single-mode fiber at the coupling point where the two types of fiber are coupled, such as a fiber optic rotary joint. This thesis suggests an artifact-reduction collimator with an expanded cladding area to reduce multipath artifacts and the artifact reduction effect was analyzed. An optimized fiber optic rotary joint was also designed using this collimator to enable artifact reduction and facilitate multimodal imaging.