Ultra-thin and flexible endoscopy probe for optical coherence tomography based on stepwise transitional core fiber

Jangbeom Lee,Yeh-Chan Ahn,Sucbei Moon,Yugyeong Chae

doi:10.1364/boe.6.001782

Jangbeom Lee, Yeh-Chan Ahn + Show 2 more

Open Access

https://doi.org/10.1364/boe.6.001782

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Abstract

We present an ultra-thin fiber-body endoscopy probe for optical coherence tomography (OCT) which is based on a stepwise transitional core (STC) fiber. In a minimalistic design, our probe was made of spliced specialty fibers that could be directly used for beam probing optics without using a lens. In our probe, the OCT light delivered through a single-mode fiber was efficiently expanded to a large mode field of 24 μm diameter for a low beam divergence. The size of our probe was 85 μm in the probe's diameter while operated in a 160-μm thick protective tubing. Through theoretical and experimental analyses, our probe was found to exhibit various attractive features in terms of compactness, flexibility and reliability along with its excellent fabrication simplicity.

Highlights

Compact, robust and reliable designs of endoscopic probes or imaging catheters have long demanded in various fields of biomedical optics
Our optical coherence tomography (OCT) probe consists of three parts after the single-mode fiber (SMF): an stepwise transitional core (STC) section, imaging fiber (IF) section and a reflector
We evaluated a potentially alternative approach of using a specialty SMF of a large core or a thermally expanded core (TEC) fiber that originated from the standard SMF

Summary

Introduction

Robust and reliable designs of endoscopic probes or imaging catheters have long demanded in various fields of biomedical optics. A graded-index multimode fiber can be spliced to an SMF as a small GRIN lens component [7,8] All those designs provide easy ways of making miniaturized robust imaging probes. A novel lens-free fiber-body OCT probe was recently proposed in a radically different scheme [4] This design takes advantage of a large-core fiber (LCF) for optimized output beam characteristics instead of using a conventional lens component. We present further improvement of the lens-free fiber-body endoscopy probe with systematic analysis on its design parameters, in emphasis of an enhanced effective imaging range and insertion loss. The optical and mechanical characteristics of our probe were found to be promising for its compactness, flexibility and reliability along with the wonderful easiness of fabrication

Probe design

Imaging fiber

Numerical simulation on fiber modes

OCT imaging test

Findings

Conclusion