title: Microlensed dual-fiber probe for depth-resolved fluorescence measurements.
abstract: We propose and demonstrate a compact microlensed dual-fiber probe that has a good collection efficiency and a high depth-resolution ability for fluorescence measurements. The probe is formed with a conventional fusion splicer creating a common focusing lens on two fibers placed side by side. The collection efficiency of the fabricated probe was evaluated by measuring the fluorescence signal of a fresh ginkgo leaf. It was shown experimentally that the proposed probe could effectively collect the fluorescence signal with a six-fold increase compared to that of a general flat-tipped probe. The beam propagation method was used to design a probe with an optimized working distance and an improved resolving depth. It was found that the working distance depends mainly on the radius of curvature of the lens, whereas the resolving depth is determined by the core diameters of the illumination and collection fibers. The depth-resolved ability of probes with working distances of ~100 μm and 300 μm was validated by using a two-layer tissue phantom. The experimental results demonstrate that the microlensed dual-fiber probe has the potential to facilitate depth-resolved fluorescence detection of epithelial tissue.
authors.affiliation: Division of Instrument Development, Korea Basic Science Institute, 113 Gwahangno, Yusung-gu, Daejeon 305-333, Korea.
authors.forename: Hae Young
authors.initials: HY
authors.lastname: Choi
authors.forename: Seon Young
authors.initials: SY
authors.lastname: Ryu
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Geon Hee
authors.initials: GH
authors.lastname: Kim
authors.forename: Seong Jun
authors.initials: SJ
authors.lastname: Park
authors.forename: Byeong Ha
authors.initials: BH
authors.lastname: Lee
authors.forename: Ki Soo
authors.initials: KS
authors.lastname: Chang
mesh_terms: D003198:Computer Simulation; D007909:Lenses; D008163:Luminescent Measurements / Q000379:methods*; D015335:Molecular Probes; D055100:Optical Fibers; D019047:Phantoms, Imaging; D013050:Spectrometry, Fluorescence
chemical_list: D015335:Molecular Probes