Fig. 1. Typical system diagram of opitcal-fiber fluorescent probe

Fig. 2. Flat-head probe structure consisting of two fibers with identical diameters

Fig. 3. Flat-head probe structure consisting of seven fibers with identical diameters. (a) Structural model; (b) micrograph of probe

Fig. 4. Structure of optical-fiber probe and fluorescence spectroscopy system

Fig. 5. Structure of multipixel opitcal-fiber probe. (a) Model diagram of end-face structure; (b) micrograph of probe^[27]

Fig. 6. Fluorescence spectroscopy system based on single double-clad optical-fiber probe

Fig. 7. Scanning electron micrographs of large-mode-field double-clad photonic crystal fiber^[29]

Fig. 8. Preparation of cone-column optical-fiber fluorescent probe by using tube etching

Fig. 9. Principle of cone-column optical-fiber probe for evanescent-wave sensing

Fig. 10. Fiber-optic scanning two-photon fluorescence endoscope. (a) Cross-section of double-clad optical-fiber probe; (b) principle of optical-fiber scanning two-photon fluorescence endoscope imaging system^[46]

Fig. 11. Two-photon fluorescence images obtained by scanning groups of neurons inside brain of Thy1-EGFP mouse by optical-fiber probe can enable a quantitative assessment of mechanical effects caused by laser scanning on neurons^[53]. (a)-(c) Field of displacements of individual neurons (whose changing positions are labeled by circles 1-4) scanned by optical-fiber probe (red); (d) close-up view of normal neurons; (e) close-up view of distorted neurons

Fig. 12. Comparison between acute and chronic diagnosis^[54]. (a) Schematic of acute diagnosis; (b) schematic of chronic diagnosis

Fig. 13. Optical-fiber-probe-based fluorescence measurement system for pesticide detection in soil^[56]. (a) Overview of measurement system; (b) taper-shaped aiguille