Two-photon endomicroscopy is an optical biopsy tool that satisfies clinical requirements for real-time subcellular-resolution imaging to assist pathological biopsy in diagnosis. Herein, we present a two-photon endomicroscopy system based on a piezoelectric ceramic tube scanner. A dual-channel amplitude-modulated sine wave drives the fiber to realize spiral scanning, a double-cladding antiresonant fiber is used for 920-nm femtosecond light-pulse low dispersion transmission, and fluorescence collection occurs with no fiber-tip engineering. The field of view is ∼200 µm, the resolution is 3.1 µm, and the frame rate is 0.7 fps. Pollen grain, GFP-labeled mouse brain section, and human stomach tissue imaging verify the capability of the two-photon endomicroscopy system.
We demonstrate a miniature fiber-optic two two-photon endomicroscopy with microsphere-spliced double-cladding antiresonant fiber for resolution enhancement. An easy-to-operate process for fixing microsphere permanently in an antiresonant fiber core, by arc discharge, is proposed. The flexible fiber-optic probe is integrated with a parameter of 5.8 mm × 49.1 mm (outer diameter × rigid length); the field of view is 210 µm, the resolution is 1.3 µm, and the frame rate is 0.7 fps. The imaging ability is verified using ex-vivo mouse kidney, heart, stomach, tail tendon, and in-vivo brain neural imaging.
Miniature two-photon microscopy combines the two-photon excitation principle and is more lightweight and flexible, allowing it to be applied to freely behaving animals. The piezoelectric tube (PZT) fiber scanner is the key actuated component in miniature fiber-scanning two-photon endomicroscopy (TPEM). In this paper, we use multi-physics field finite element simulation to model and analyze a reverse-fixed PZT fiber scanner for TPEM. The simulation results show that the first two resonant frequencies of the PZT fiber scanner are 163.6 Hz and 757.9 Hz, respectively. At the first two resonant points, the PZT fiber scanner scan range are 0.078 mm and 0.68 mm, respectively. Theoretical guidance for frequency selection of the reverse-fixed PZT fiber scanner is provided by these simulation results.
Piezoelectric ceramic tube fiber-scanning two-photon endomicroscopy is an essential division of miniature two-photon microscopy. The reverse collection optical path of the two-photon endomicroscopy platform is modeled and designed in this study. After simulating the chromatic aberration characteristics of the objective, the effects of the collection signal wavelengths, off-axis positions, fiber cladding diameters, and imaging depths on the collection efficiency are evaluated using Monte Carlo simulation. The results provide an additional theoretical explanation for enhancing the two-photon endomicroscopy platform's imaging sensitivity and signal-to-noise ratio.
In recent years, two-photon endomicroscopy has developed as a promising label-free optical biopsy technique for diagnosing gastrointestinal tumors. In this study, we optimize the imaging resolution of the lensed fiber-optic scanning two-photon endomicroscopic imaging scheme. By fabricating a lensed fiber for fiber-optic scanning two-photon endomicroscopy, a lateral resolution of 2.1 μm and a field of view of 600 μm in two-photon endomicroscopic imaging is achieved. Furthermore, the objective-lens-free imaging capability is also validated using gastric
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