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Qiaofeng Tan

Publications and source records attributed to Qiaofeng Tan.

4 recordsLinked to original sources

Spatiotemporally decoupled super-oscillatory microscopy enables label-free reconstruction of human ciliary waveforms

Imaging native motile cilia requires label-free contrast, sub-diffraction spatial discrimination, and millisecond temporal sampling. We introduce Super-Oscillatory Label-free Inertia-free Scanning (SOLIS) microscopy, in which a static multilevel diffractive optical element generates compressed super-oscillatory probes and a high-speed digital micromirror device addresses the probes without translated-stage motion. A complete 25-position scan produces one acquisition-window-averaged map every 3.58 ms, corresponding to 279 reconstructed fps. On nanofabricated line-pair targets, SOLIS retained measurable label-free contrast at a 253 nm period and resolved representative modulation at 270 nm. In differentiated primary human nasal epithelial cultures, SOLIS distinguished adjacent ciliary maxima separated by 346 nm, below the 431 nm Rayleigh reference, and acquired 14-16 reconstructed samples per observed beat cycle. Tip-centroid tracking recovered closed, asymmetric two-dimensional trajectories with a median cycle-to-cycle localisation precision of 63.5 nm across 20 cilia. In a proof-of-principle perturbation, Dynarrestin reduced culture-level ciliary beat frequency from 19.2 to 6.6 Hz and projected stroke amplitude from 4.8 to 2.3 um. By separating spatial compression from temporal addressing, SOLIS extends super-oscillatory microscopy to label-free, millisecond-scale analysis of human ciliary kinematics.

physics.optics

Mechanical-scan-free and multi-color super-resolution imaging with diffractive spot array illumination

Point-scanning microscopy approaches are transforming super-resolution imaging. Despite achieving parallel high-speed imaging using multifocal techniques, efficient multi-color capability with high-quality illumination is currently lacking. In this paper, we present for the first time Mechanical-scan-free and multi-Color Super-resolution Microscopy (MCoSM) by spot array illumination, which enables mechanical-scan-free super-resolution imaging with adjustable resolution and field of view (FoV) based on spatial light modulators (SLMs). Through 100s-10,000s super-resolution spot illumination with different FoV for imaging, we demonstrate the adjustable capacity of MCoSM. MCoSM extends current spectral imaging capabilities through a time-sharing process of different color illumination with phase-shifting scanning, while retaining the spatial flexibility of super-resolution imaging with diffractive spot array illumination. To showcase the prospects for further combining MCoSM with multi-color imaging, we also perform spectral unmixing (four-colors) on images of fluorescent beads at high resolution. MCoSM provides a versatile platform for studying molecular interactions in complex samples at the nanoscale level.

physics.optics

High-fidelity far-field microscopy at λ/8 resolution

The emergence of far-field super-resolution microscopy has rejuvenated the possibility for nanoscale imaging. Approaches to far-field super-resolution that utilize point scanning often depends on spatially reducing the size of the focused spot. However, the focused spot always achieves high resolution at the expense of extremely low light efficiency for the probing mainlobe and high-intensity sidelobes, which limits the applications in nanoscale imaging and might cause misinterpretation of samples. Here we report a sharp probing spot with the diffraction efficiency of 3.76% at the resolution of 38% of the Airy spot size assisted by the two-dimensional multi-level diffractive optical element (DOE) experimentally. The diffraction efficiency of DOE is improved by at least two orders of magnitude at the same resolution by breaking the limitation of circular 0-π binary structure superoscillatory lens. To eliminate the influence of the high-intensity sidelobes, high-fidelity images are reconstructed based on the modified deconvolution algorithm by virtue of the prior-knowledge. Finally, high-fidelity far-field microscopy (HiFi-FM) is constructed and experimental results show that HiFi-FM allows the resolution of spatially complex samples better than 69 nm while acquiring high fidelity.

physics.optics

Helicity Dependent Directional Surface Plasmon Polariton Excitation Using A Metasurface with Interfacial Phase Discontinuity

Surface plasmon polaritons (SPPs) have been widely exploited in various scientific communities, ranging from physics, chemistry to biology, due to the strong confinement of light to the metal surface. For many applications it is important that the free space photon can be coupled to SPPs in a controllable manner. In this Letter, we apply the concept of interfacial phase discontinuity for circularly polarizations on a metasurface to the design of a novel type of polarization dependent SPP unidirectional excitation at normal incidence. Selective unidirectional excitation of SPPs along opposite directions is experimentally demonstrated at optical frequencies by simply switching the helicity of the incident light. This approach, in conjunction with dynamic polarization modulation techniques, opens gateway towards integrated plasmonic circuits with electrically reconfigurable functionalities.

physics.optics