Lens-free endoscopy probe for optical coherence tomography

Abstract

We present an ultrathin fiber-optic endoscopy probe for optical coherence tomography (OCT), which is made of a series of fused optical fibers instead of the conventional scheme based on an objective lens. The large-core fiber with a core diameter of 20 µm was utilized for the probe, while a single-mode fiber of core diameter 8.2 µm mainly delivered the OCT light. Those fibers were spliced with a bridge fiber of an intermediate core size. The guided light was stepwise converted to a beam of a large mode-field diameter to be radiated with a larger depth of focus. We obtained a 125 µm thick all-fiber endoscopy probe with a side-viewing capability implemented by an angled fiber end. Successful OCT imaging was demonstrated with a swept-source OCT system and showed the practical applicability of our lens-free endoscopy probe.

Characterization of eosinophilic esophagitis murine models using optical coherence tomography

“…OCT images of murine esophagus can be recorded in vivo using 0.9 mm external diameter catheters containing an OCT ImageWire (St. Jude Medical Inc., St. Paul, Minnesota, USA), which is widely used in cardiovascular OCT for imaging coronary arteries and deployed stents [61,62]. Moreover, miniature endoscopes capable of providing high quality OCT images have been designed and developed using lens-free large core fibers (360 µm probe) [63]. Using these miniature probes, OCT permits in vivo and longitudinal studies in murine GI disease models, which can provide critical information related to pathogenesis, disease progression and treatment effects.…”

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

“…Additionally, the distal end face of the optical fiber was polished at a 49-degree angle ( ϕ ) to achieve total internal reflection. Based on our previous lens-free probe designs, the polishing angle was slightly deviated from 45 degree to reduce back reflection from the fiber cladding and the sheath surface 19 , 22 . A metal housing was placed outside the optical fiber to reduce friction during rotational scanning and minimize non-uniform rotational distortion from degrading the image.…”

“…The axial and lateral resolutions of the probe are 6.8 um and 34 um in air, respectively, when the target is placed at a distance of 0.5 mm. Detailed characterizations of the fiber optic probe with a similar design have been described in a previous paper 22 .

Figure 1 Bare-fiber OCT probe.

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Miniature forward-viewing common-path OCT probe for imaging the renal pelvis

“…The outer diameter of the probe should be less than 1 mm to fit through the working channel of a flexible ureteroscope. Although OCT probes smaller than 1 mm are challenging to fabricate with good optical properties, previous work has demonstrated that it is feasible (e.g [6][7][8][9][10].). Small (<1 mm diameter), side-viewing scanning endoscopic probes have been reported [7,9], but not forward-viewing.…”

“…Although OCT probes smaller than 1 mm are challenging to fabricate with good optical properties, previous work has demonstrated that it is feasible (e.g [6][7][8][9][10].). Small (<1 mm diameter), side-viewing scanning endoscopic probes have been reported [7,9], but not forward-viewing. Scanning forward-viewing probes have been demonstrated using various technologies such as PZT actuators [11], MEMS mirrors [12], counter-rotating wedges [6], magnetic coils [8] and rotating torque cables [13], however all of them are either too large [11][12][13], or not flexible [6,8], and thus are not suitable for deployment through a flexible ureteroscope.…”