Ultrafast quasi-three-dimensional imaging

Abstract

Understanding laser induced ultrafast process with complex three-dimensional (3D) geometrical and extreme property evolution offers unique platform to explore novel physical phenomena and to overcome manufacturing limitations. Ultrafast imaging has been considered as an effective tool due to their exceptional spatiotemporal resolution ability. However, the current imaging techniques with single view imaging actually projecting 3D information on two-dimensional plane, leading to great information loss, and misunderstanding the nature of ultrafast process. Here, we propose a quasi-3D imaging method to describe the 3D ultrafast process and further analyse spatial asymmetric of laser induced plasma. The vertically polarization laser pulses are adopted to illuminate reflection-transmission views, and the binarization techniques are employed to extract contours, forming the corresponding two-dimensional matrix. By rotating and multiplying the two-dimensional contour matrices obtained from the dual views, the quasi-3D image was reconstructed. It successfully unveils dual phase transition mechanisms and elucidates the diffraction phenomena occurring outside the plasma. Furthermore, the quasi-3D image confirms spatial asymmetric of plasma in picosecond plasma, which is hard to acquire in two-dimensional images. Our findings demonstrate that quasi-3D imaging not only offers a more comprehensive understanding of plasma dynamics than previous imaging methods, but also has widespread potential in various ultrafast fields such as strong-field physics, fluid dynamics, and cutting-edge manufacturing.

Self-propelled Leidenfrost droplets on femtosecond-laser-induced surface with periodic hydrophobicity gradient

“…Nanoscale particles cover the surface due to Coulomb explosion during femtosecond laser ablation, allowing for easy fabrication of hierarchical structures without complex lithography procedures [41,42]. Figure 2(a) displays topographies under different femtosecond laser power and corresponding magnified images.…”

Wide-Size Range and High Robustness Self-Assembly Micropillars for Capturing Microspheres

“…These methods are either costly, complicated and cumbersome steps, or cannot arbitrarily design the structure size and pattern shape, resulting in low controllability and flexibility. A femtosecond laser has the advantages of high resolution, good scalability, and strong controllability, − making it one of the best choices for processing capillary force driven self-assembly microstructures. − For example, Hu et al fabricated self-assembly micropillar structures in photopolymers by femtosecond laser two-photon polymerization (TPP), with a structural height of 2–7 μm, which can capture the diameter of microspheres in 1–4.6 μm and can only capture microspheres with a diameter of less than 5 μm. Subsequently, Ni et al and Hu et al improved the efficiency of TPP technology to manufacture micropillar structures through different shaping optical fields, and its structural height was roughly 2–13 μm, the diameters of the captured microspheres were 5–10 μm, and the capture range was only slightly widened, which was still difficult to meet the requirements for the capture of larger size microspheres in practical applications.…”

Controllable Photoreduction of Graphene Oxide/Gold Composite Using a Shaped Femtosecond Laser for Multifunctional Sensors

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