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[Display omitted] • Broadband light absorption surface is obtained from cross-scale micro-/nanostructures fabricated by femtosecond laser. • Light absorption mechanism is numerically and experimentally studied. • Photo-thermal-electric conversion efficiency of a Seebeck device is improved with such surface integrated on. • Performance parameters and device design of a thermoelectric photodetector are explored. The limited sensitivity and inherent long response time restrict the widespread applicability of thermally-based photodetectors. Herein, a copper surface endowed with optical absorption enhancement by femtosecond laser fabrication is introduced, to improve the sensitivity and power prediction speed of thermoelectric photodetectors. Cross-scale microstructures including periodic micro-taper array and randomly dispersed particles are obtained on the surface, and their formation mechanism is elucidated. The surface exhibits an average reflectivity of 8% over the wavelength range of 200–2500 nm. This broadband absorption is mainly due to the local light field enhancement by the unevenly oxidized and size-dispersed particles, while the periodic micro-taper array further enhances the absorption by geometric light trapping effect. When integrated into a thermoelectric device, a comprehensive parameter analysis including sensitivity (45.053 mV/W), response time (5.47 s), precision of time-dependent prediction (2 s to obtain R 2 ⩾ 0.999), and precision of measuring at different points (3.97%) is performed. Our study offers a practical approach to produce cross-scale light absorption microstructure, paving the way for its promising advances in photothermal-based optoelectronic applications. [ABSTRACT FROM AUTHOR]

• A simple and robust method for fabricating patterned superhydrophobic surfaces by femtosecond laser micromachining is presented. • The wettability and the adhesion force of the patterned surface are tuned by changing the width of the linear pattern. • Based on the modified Furmidge equation, the relationship between the adhesion and the liquid-solid interface width is explained. • The patterned surface has the ability to manage fluid motion, transportation and mixing. Patterned superhydrophobic surfaces have a wide range of applications in terms of microfluidic devices. In this work, a simple and robust method is proposed to fabricate patterned superhydrophobic surfaces by two combined steps including femtosecond laser microfabrication and immersion treatment. The obtained surface exhibits contact angles of 170.0°, 167.6°, and 169.5°, and sliding angles of 5.8°, 6.0°, and 3.9° for 12 μL, 18 μL, and 30 μL water droplets, respectively. The high-adhesion hydrophobic linear pattern combined with the surrounding low-adhesion superhydrophobic surface exhibits controllable wettability and pronounced liquid-sliding anisotropy. Since the contact angle and the adhesion force can be controlled by adjusting the width of the linear pattern, the droplet motion can be directionally modulated. As the line width increases, the sliding angle in parallel direction can be regulated from 18.9° to 90°, from 15.3° to 47.6°, and from 8.6° to 25.0° for 12 μL, 18 μL, and 30 μL water droplets, respectively. Based on the modified Furmidge equation, the relationship between adhesion and liquid-solid interface width can be reasonably explained. Furthermore, the potential applications of the patterned surfaces for droplet transport and mixing are explored. The wettability of the superhydrophobic surfaces to liquids of different types and pH is also investigated. The work presented here has the potential to advance femtosecond laser scanning as a simple, precise, and controllable method for fabricating patterned superhydrophobic surfaces, and to accelerate their applications in parallel reactors, chemical micro-assays, drug delivery systems and so on. [ABSTRACT FROM AUTHOR]

• Size regulation of fs-LDW grooves on ZnS is realized by wet chemical etching. • Surface roughness of microgroove sidewalls is reduced. • Emerging of microcracks is observed during etching process. In this paper, wet chemical etching is employed to treat femtosecond (fs) laser fabricated surface microstructure on zinc sulfide (ZnS) to improve its surface quality (surface roughness) and regulate its size (depth/width ratio). Dilute nitric acid (HNO 3) solution is selected as the etchant. First, the surface morphology of microgrooves before and after etching is observed as a function of etching time. Surface microcracks are also observed. Then, under different etchant concentrations, the size evolution of the microgrooves is measured for different etching time. Finally, an explanation for the changes in surface quality and size caused by etching is provided. [ABSTRACT FROM AUTHOR]

In this paper, one-step fabrication of fusiform hierarchical micro/nanostructures on copper surface by femtosecond laser is proposed. According to the preferential valley ablation, Marangoni effect based on melt hydrodynamics and the coupling of the incident light and surface plasmon polaritons, the formation mechanism of the fusiform hierarchical micro/nanostructures is explained. And the effect of laser parameters including the defocusing distance, laser power, and scanning speed on the surface morphology is investigated. Also, the quantitative analysis of the fusiform tapers is carried out. It is demonstrated that the three-dimensional size of the fusiform hierarchical micro/nanostructures could be controlled by adjusting laser parameters. In addition, the potential applications of the fusiform hierarchical micro/nanostructures in microliter droplet directional transportation and light absorption are explored. • One step fabrication of fusiform hierarchical micro/nanostructures on Cu by fs laser is proposed. • The formation mechanism of the micro/nanostructures is explained by Marangoni effect and surface plasmons model. • Effect of laser parameters on the three-dimensional micro/nanostructures' size is investigated. • The potential applications of the micro/nanostructures in droplet transportation and light absorption are explored. [ABSTRACT FROM AUTHOR]

The method of collecting aerial images or videos by unmanned aerial vehicles (UAVs) for object search has the advantages of high flexibility and low cost, and has been widely used in various fields, such as pipeline inspection, disaster rescue, and forest fire prevention. However, in the case of object search in a wide area, the scanning efficiency and real-time performance of UAV are often difficult to satisfy at the same time, which may lead to missing the best time to perform the task. In this paper, we design a wide-area and real-time object search system of UAV based on deep learning for this problem. The system first solves the problem of area scanning efficiency by controlling the high-resolution camera in order to collect aerial images with a large field of view. For real-time requirements, we adopted three strategies to accelerate the system, as follows: design a parallel system, simplify the object detection algorithm, and use TensorRT on the edge device to optimize the object detection model. We selected the NVIDIA Jetson AGX Xavier edge device as the central processor and verified the feasibility and practicability of the system through the actual application of suspicious vehicle search in the grazing area of the prairie. Experiments have proved that the parallel design of the system can effectively meet the real-time requirements. For the most time-consuming image object detection link, with a slight loss of precision, most algorithms can reach the 400% inference speed of the benchmark in total, after algorithm simplification, and corresponding model's deployment by TensorRT. [ABSTRACT FROM AUTHOR]

Bessel beam femtosecond lasers being non-diffractive are well-suited for drilling high aspect ratio microholes with minor thermal impact. Hereby, the Bessel beams with different non-diffraction lengths using axicon lenses were generated with different taper angles for analyzing the drilled microholes to optimize the aspect ratio. The experimental results show that the depth of microhole is increasing with the pulse number accumulating for low energy laser pulses. With the increasing of energy laser pulse, the increment of microhole diameter is faster than that of the depth. The large aspect ratio microholes with the maximum value of 348:1 have been formed by Bessel femtosecond laser micromachining. [ABSTRACT FROM AUTHOR]

• Convex grid-patterned microstructures are processed by fs laser and chemical etching. • According to Raman spectra, the formation of the microstructures is investigated. • The effect of experimental parameters on the microstructures' 3D size is discussed. • The hydrophobic property of a surface with such microstructures is explored. The convex grid-patterned microstructures were fabricated on a silicon substrate by using femtosecond laser assisted with chemical etching in this study. Along the femtosecond laser scanning traces, the isosceles trapezoidal microstructures were generated. According to Raman spectra and elemental distribution, the formation of the convex microstructures is investigated. Also, the effect of experimental parameters including laser power, scanning speed, etching duration and etching temperature on the microstructures' three-dimensional size is discussed in detail. In addition, the hydrophobic property of a surface with large-area convex grid-patterned microstructures was explored. [ABSTRACT FROM AUTHOR]