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

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.

Automated 3D segmentation of methyl isocyanate-exposed rat trachea using an ultra-thin, fully fiber optic optical coherence endoscopic probe

“…Since toxic gas inhalation often causes airway obstruction and narrowing, the anatomical structure of the airway is severely restricted, which makes it difficult for most endoscopic OCT probes to pass through. We adopted a previously proposed lens-free probe design 19 and optimized it for examining the rat airway. In this probe, a stepwise transitional core structure was utilized instead of a focusing lens to reduce the divergence of light and increase the lateral resolution of the probe.…”

“…Recently, Lee et al . proposed an all fiber optic endoscopic design for an ultra-thin imaging OCT probe 19 . This design utilizes a large-core fiber and a stepwise transitional core structure to create a compact and flexible OCT endoscopy probe with a diameter of less than 1 mm.…”

Lamellar keratoplasty using position-guided surgical needle and M-mode optical coherence tomography

“…This structure is advantageous in its compactness, ease of fabrication, and operational reliability, though with a moderate sacrifice of the imaging range. The STC fiber supported an effective imaging range of 0.9 mm with beam diameter of ∼25 μm in corneal tissue (n ¼ 1.35), 32 so was sufficient for our application to corneal imaging. The fabricated fragile fiber structure was reinforced by a metal jacket with an outer diameter of 200 μm.…”

“…1(a)], which produces an output beam without using a lens element. 32 It was composed of three different optical fibers with an outer diameter of 125 μm, spliced in series to the standard single-mode fiber of light delivery. The large core fiber with its diameter of 29 μm at the distal end directly determined the characteristics of the output beam while keeping the effective single-mode guidance through the STC structure.…”

Etching-enabled extreme miniaturization of graded-index fiber-based optical coherence tomography probes

“…However, the fabrication process is challenging since precise positioning and fixing of a microsphere to the tip of the etched SM fiber is required. Lee et al 10 used chemical etching to miniaturize lensless side viewing probes, composed of three different fiber components of progressively increased core diameter. These probes significantly extend the effective imaging depth compared to a SM fiber.…”