Microlensed dual-fiber probe for depth-resolved fluorescence measurements

Area of Science:

• Optics and Photonics
• Biomedical Engineering
• Fluorescence Spectroscopy

Background:

• Accurate fluorescence measurements are crucial for biological and medical diagnostics.
• Existing fiber probes often face limitations in collection efficiency and depth resolution.
• Developing advanced optical probes is essential for in-situ tissue analysis.

Purpose of the Study:

• To propose and demonstrate a compact microlensed dual-fiber probe.
• To enhance collection efficiency and depth-resolution ability for fluorescence measurements.
• To optimize probe design for improved working distance and resolving depth.

Main Methods:

• Fabrication of a microlensed dual-fiber probe using a conventional fusion splicer.
• Evaluation of collection efficiency using fluorescence measurements of a ginkgo leaf.
• Design optimization using the beam propagation method.
• Validation of depth-resolved ability using a two-layer tissue phantom.

Main Results:

• The microlensed probe achieved a six-fold increase in fluorescence signal collection compared to a flat-tipped probe.
• Optimized probe design led to improved working distance and resolving depth.
• Depth-resolved detection was successfully demonstrated using tissue phantoms at working distances of ~100 μm and 300 μm.

Conclusions:

• The compact microlensed dual-fiber probe offers superior collection efficiency and depth resolution.
• The probe design parameters, including lens curvature and fiber core diameters, critically influence performance.
• This technology shows significant potential for depth-resolved fluorescence detection in epithelial tissue.