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

Area of Science:

• Biomedical Engineering
• Optical Engineering
• Medical Imaging

Background:

• Optical coherence tomography (OCT) requires specialized probes for in-situ imaging.
• Existing OCT probes can be bulky or complex, limiting their application in minimally invasive procedures.
• The development of compact and flexible OCT probes is crucial for advancing endoscopic imaging.

Purpose of the Study:

• To design and fabricate an ultra-thin fiber-body endoscopy probe for OCT.
• To achieve a minimalistic probe design without external lenses.
• To evaluate the probe's performance in terms of size, beam characteristics, and reliability.

Main Methods:

• Utilized a stepwise transitional core (STC) fiber for the probe's core.
• Spliced specialty fibers to create a lensless beam probing system.
• Integrated the STC fiber probe within a 160-μm thick protective tubing.
• Characterized the probe's optical performance, including mode field expansion and beam divergence.

Main Results:

• Achieved an ultra-thin probe diameter of 85 μm.
• Expanded OCT light to a 24 μm mode field diameter with low beam divergence.
• Demonstrated a minimalistic, lensless design using spliced specialty fibers.
• Confirmed probe compactness, flexibility, and reliability through theoretical and experimental analysis.

Conclusions:

• The developed STC fiber-based OCT probe offers a simple, compact, and flexible solution for endoscopic imaging.
• The lensless design and minimalistic construction enhance probe reliability and ease of fabrication.
• This ultra-thin probe has significant potential for various minimally invasive OCT applications.