Laser shock peening is an effective surface technology for improving the surface mechanical properties of metals. Many studies have been performed to process different kinds of metallic material that can induce compressive residual stress in the top layer of samples, which would extend the fatigue life of metal parts in the industry. The titanium alloy samples are treated by laser shock peening with water layer as constraint layer and without protective coating in this research, after which the titanium alloy samples are observed and analyzed with a scanning electron microscope, hardness tester, laser confocal microscope, and wear tester. The surface roughness, surface microstructure, and other properties of untreated and treated titanium alloy are compared to study the effect on titanium alloy of laser shock peening process without protective coating.
As the third generation of photovoltaic cell technology, the Perovskite Solar Cells (PSCs) have strong theoretical advantages compared with discrystalline silicon and thin film cells because of their material characteristics. In the formation of the series structure of perovskite cells, different film layers need to be marked at different positions. The scribing of functional layers can be done by mask plate, chemical etching, mechanical or laser scribing. Laser scribing can produce finer scribing areas. At present, laser scribing has gradually replaced other scribing methods and become the main scribing methods. In this paper, laser scribing for the realization of all the P1, P2, and P3 scribes are reported by optical fiber femtosecond laser with output wavelengths of 532 nm, and pulse width is adjustable at 300 fs. The better processing parameters are found for the scribing speed of 2000 mm/s, and the laser power of 1.8 W for the P1 scribe. High precision scribing with slit width less than 10 μm is obtained by optimizing scribing speed and laser power. All the results indicate that laser scribing would play an important role in achieving high performance PSCs modules in which the interconnects.
At present, laser cutting has emerged as a new technology in the field of glass cutting to achieve a good quality and high efficiency, that is believed to have a very broad application prospect. In this report, the glass cutting by picosecond laser with a high peak power and a long focal-depth Bessel beam was studied. The maximum power of laser is chosen to be 50 W with a spot size of 2 mm, pulse width of 10 ps, and wavelength of 1064 nm. The frequency is adjustable in the range of 50 KHz to 200 KHz. The factors affecting the cutting roughness was analyzed, including the focus position, speed, and power. Meanwhile, the glass is split by a carbon dioxide laser with the wavelength of 10.6 μm and maximum power is 100 W, which breaks due to internal stress induced by heating. By adjusting the speed, power and focusing position, the good processing parameters for the ultra-white glass with thickness of 4 mm were found. High quality cutting with minimum edge breakage less than 3 μm is confirmed by microscope. Moreover, nonstandard-shaped cutting and straight line cutting with a high speed of 300 mm/s have also achieved in this work. All results demonstrates that ultra-fast laser is a promising tool for glass cutting.
We demonstrate comparatively the laser performance of 970 nm laser diode (LD) side-pumped Er:YSGG crystals with a length of 85 mm and diameters of 2, 3, and 4 mm. The maximum average powers of 25.18, 25.74, and 20.41 W are achieved at 150 Hz and 200 μs, corresponding to the slope efficiencies of 30.01%, 31.47%, and 24.38%, respectively. The experimental results show that the Er:YSGG crystal rod with a diameter of 2 mm has no obvious advantage in laser output at low frequency and low pump power because the gain volume is small and the pump power cannot be fully absorbed, resulting in the gain saturation phenomenon. However, it exhibits the best laser output under high repetition rate and high pump power. The average power of 16.47 W obtained at 500 Hz is still not saturated. The beam quality factors M2 in the x and y direction are determined to be 3.15/3.12, respectively, which is significantly better than those of the rods with diameters of 3 and 4 mm. All the results indicate that the crystal rod with a smaller diameter has better thermal management due to its larger specific surface area and better cooling ability, which is conducive to improving laser performance under the high repetition rate and high pump power operation.
Electronic ceramic substrates have been widely used in various markets, which include the automotive industry, electronics, aviation, and sensor due to their good thermal conductivity and thermal stability. The holes in ceramic substrates are very important for their application, many techniques are studied to drill holes of different sizes. This research presents the results of UV ultrashort pulse laser drilling of ceramic substrates with different laser parameters. Normally, the ultrashort pulse laser can be used to process materials due to its less heat-affected zone, so the heat-affected zone of the hole is also observed around the laser-drilled holes.
This paper reports ex-situ preparation of conductive polymer/single-walled carbon nanotubes (SWNTs) nanocomposites by adding high conductive SWNTs to the polymer matrix. Sonication methods were used to disperse the SWNTs in the polymer. The conductivity of the nanocomposites is tuned by increasing the concentration of SWNTs. Furthermore, we present two-photon polymerization (2PP) method to fabricate structures on the basis of conductive photosensitive composites. The conductive structures were successfully generated by means of 2PP effect induced by a femtosecond laser.
Microassembling with holographic optical tweezers (HOT) is a flexible manufacturing technology for the precise
fabrication of complex microstructures. In contrast to classical direct writing techniques, here, microparticles are
transported within a fluid to appropriate positions, where they are finally bound. Therefore, optical forces act against the
inner friction of the fluid. This effect limits the microassembling process in the meaning of process speed. In this work
we investigate these limitations depending on the applied laser power and particle size. Additionally, different to
conventional optical tweezers, HOTs use spatial light modulators (SLM) to control the laser beam and the object's
position. This is performed at discrete step sizes caused by successively imaging respective kinoforms on the SLM at
specific refresh rates. An optimization of the step size and the applied update rate are crucial to reach maximum
velocities in particle movement. Therefore, the performance of dynamic particle manipulation is investigated in
individual experiments. Stable manipulation velocities of up to 114 μm/s have been reported in our work using 6 μm
polystyrene particles and an applied laser power of 445 mW.
This work reports the preparation of polymer/TiO2 nanocomposite by adding TiO2 nanoparticles to the polymer matrices.
TiO2 nanoparticles can be effectively dispersed into the polymer. The refractive index of the nanocomposites can be
tuned by increasing the concentration of TiO2 nanoparticles. The prepared samples exhibit excellent optical transparency
in the Vis-NIR region, i.e. at two-photon polymerization (TPP) processing wavelength, and can be used to write threedimensional
structures by means of TPP. Structures with high refractive index have been produced with the novel ultrahigh
resolution technology based on TPP processing of polymer/TiO2 nanocomposites.
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