Abstract
.We introduced and validated a method to miniaturize graded-index (GRIN) fiber-based optical coherence tomography (OCT) probes down to in diameter. The probes consist in an assembly of single-mode (SM), coreless (CL), and graded-index (GRIN) fibers. We opted for a probe design enabling controlled size reduction by hydrogen fluoride etching. The fabrication approach prevents nonuniform etching for both the GRIN and SM fiber components, while it requires no probe polishing postetching. We found that the miniaturized probes present insignificant loss of sensitivity () compared to their thicker () counterparts. We also showed that their focusing capabilities remain tunable and highly predictable. The fabrication process is simple and can be carried out by using inexpensive telecom equipment. Both the fabrication process and the developed probes can benefit the prototyping of minimally invasive endoscopic tools.
Highlights
Optical coherence tomography (OCT) is a noninvasive tomographic imaging technique based on low-coherence optical interferometry.[1]
Contrary to the etching-enabling approach, the GRIN fiber core is exposed to hydrogen fluoride (HF)
These results demonstrate that the morphology of the miniaturized probes remains unaffected compared to their thicker counterparts if (i) an etching-enabling design is employed and (ii) the miniaturization limit, imposed by the GRIN core diameter, is respected
Summary
Optical coherence tomography (OCT) is a noninvasive tomographic imaging technique based on low-coherence optical interferometry.[1]. It enables fabrication of probes with controlled optical properties in both forward and side viewing imaging configurations.[5,6] Even though 80-μm SM fibers are today commercially available, the smallest commercially available GRIN and CL fibers remain 125 μm in diameter This imposes a 125-μm miniaturization limit for focusing GRIN-based OCT probes fabricated with a splicing approach. 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. Given the versatility and wide use of GRIN-based probes, the development of a simple fabrication approach facilitating extreme miniaturization without compromising the simplicity and tunability of a GRIN-based design can benefit a variety of OCT applications It can enable integration with minimally invasive medical needles. Probes possess tunable optical properties, uncompromised compared to their thicker counterparts
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