- 标题
- 摘要
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- 实验方案
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Advanced multimodal laser imaging tool for urothelial carcinoma diagnosis (AMPLITUDE)
摘要： The paper presents an overview and concept of the European Union Horizon 2020 project “AMPLITUDE - Advanced Multimodal Photonics Laser Imaging Tool for Urothelial Diagnosis in Endoscopy”. The project aims at the development of a novel label-free, multi-modal imaging tool for urothelial cancer diagnosis and therapy monitoring based on ultrafast fiber laser operating in the 3rd biological window with frequency doubling and additional 785 nm CW laser for Raman spectroscopy. The tool corresponds to clinical needs for better diagnosis of the pathohistological staging of tumours and in-vivo endoscopic assessment of depth of lesion invasiveness.
关键词： 3rd biological window,multiphoton imaging,bladder cancer,confocal microscopy,short-pulsed laser
更新于2025-09-19 17:13:59
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Production and Tribological Characterization of Tailored Laser-Induced Surface 3D Microtextures
摘要： The aim of the present study was firstly to determine the manufacturing feasibility of a specific surface 3D-microtexturing on steel through an ultra-short pulsed laser, and secondly to investigate the tribological properties under 2 different lubrication conditions: oil-lubricated and antifriction coated. The selected 3D-microtexture consisted of 2 different levels of quadratic micropillars having side dimensions of approximately 45 μm, heights of about 35 μm and periods of 80 μm. It was shown that the production of specific 3D-microtextures on steel substrates using an ultra-short pulsed laser was feasible, and that the reproducibility of the texture dimensions over the entire textured region was extremely good. Frictional investigations have shown that, in comparison to the benchmark (untextured samples), the 3D-microtextured samples do not induce any significant improvements in the coefficient of friction (COF) under oil-lubricated conditions, but that under antifriction coated conditions, significant improvements in the friction coefficients may be achieved. Wear-based tribological tests have shown that the antifriction coating on benchmark samples was completely depleted, which greatly influenced their friction and wear behavior, since steel-steel contact occurred during testing. For the 3D-microtexture, the antifriction coating was also partially depleted; however, it accumulated itself in the microtexture which acted as a potential lubricant reservoir.
关键词： ultra-short pulsed laser,surface characterization,wear,laser microtexturing,tribological,friction,characterization
更新于2025-09-16 10:30:52
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Laser-assisted micro-milling of austenitic stainless steel X5CrNi18-10
摘要： This paper presents a novel Laser-Assisted Micro-Milling (LAMM) process of austenitic stainless steel X5CrNi18-10. The LAMM process is compared with the conventional micro-milling process. Ultra-short pulsed laser radiation is utilized for the structuring of the workpiece surface prior to the micro-milling process. Different laser structures are produced on the workpiece surface at a constant laser scanning speed with various laser powers and laser line spans. The high performance of the developed process is shown by experimental investigations. The effect of laser structuring on the micro-milling forces and temperature indicated the superior performance of the new LAMM process. Cutting forces and temperature could be reduced by up to 70% and 50%, respectively. The results of conventional micro-milling showed that increasing the cutting speed, at a constant undeformed chip thickness, reduced the micro-milling forces. Increasing the cutting speed from 50 to 250 m/min halved both the trust and normal forces, while it slightly improved the surface roughness. On the other hand, increasing the feed per tooth degraded the surface roughness and increased the cutting forces. Furthermore, in conventional milling the workpiece was subjected to high plastic deformation during the cutting process, while side flow, smeared material, metal debris, and cavities were observed on the workpiece surface.
关键词： Laser-assisted micro-milling,Austenitic stainless steel,Ultra-short pulsed laser,Laser structuring,Micro-milling
更新于2025-09-12 10:27:22
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Grain refining in weld metal using short-pulsed laser ablation during CW laser welding of 2024-T3 aluminum alloy
摘要： The 2024 aluminum alloy is used extensively in the aircraft and aerospace industries because of its excellent mechanical properties. However, the weldability of 2024 aluminum alloy is generally low because it contains a high number of solutes, such as copper (Cu), magnesium (Mg), and manganese (Mn), causing solidification cracking. If high speed welding of 2024 aluminum alloy without the use of filler is achieved, the applicability of 2024 aluminum alloys will expand. Grain refining is one of the methods used to prevent solidification cracking in weld metal, although it has never been achieved for high-speed laser welding of 2024 aluminum alloy without filler. Here, we propose a short-pulsed, laser-induced, grain-refining method during continuous wave laser welding without filler. Bead-on-plate welding was performed on a 2024-T3 aluminum alloy at a welding speed of 1 m min?1 with a single mode fiber laser at a wavelength of 1070 nm and power of 1 kW. Areas in and around the molten pool were irradiated with nanosecond laser pulses at a wavelength of 1064 nm, pulse width of 10 ns, and pulse energy of 430 mJ. The grain-refinement effect was confirmed when laser pulses were irradiated on the molten pool. The grain-refinement region was formed in a semicircular shape along the solid–liquid interface. Results of the vertical section indicate that the grain-refinement region reached a depth of 1 mm along the solid–liquid interface. The Vickers hardness test results demonstrated that the hardness increased as a result of grain refinement and that the progress of solidification cracking was suppressed in the grain refinement region.
关键词： grain refinement,short pulsed laser,laser welding,laser ablation,2024 aluminum alloy,hot cracking,dendrite fragmentation
更新于2025-09-12 10:27:22
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Preparing TEM Specimens and Atom Probe Tips by Laser Machining
摘要： Preparation of electron-transparent thin specimens can be costly in terms of time and is often challenging. Materials and products are becoming more complex, and device components are getting smaller each year. On the other hand, analysis and diagnostic methods become more exacting. Lack of time and high costs for diagnostics force companies to speed up, simplify, and customize the analysis process. Ultra-short-pulsed laser-based sample preparation can speed up the process and make possible new sample geometries. This article shows the advantages of this technology and how it can be used to prepare TEM lamellas (H-Bar) and multiple APT tips or pillars.
关键词： ultra-short-pulsed laser,laser ablation,APT tips,heating effects,TEM lamellas
更新于2025-09-12 10:27:22
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Control of short-pulsed laser induced periodic surface structures with machining -picosecond laser nanotexturing with magnetic abrasive finishing-
摘要： An active area of research is the altering of surface functions (e.g., wettability and cell adhesion) by controlling fine surface structures such as laser-induced periodic surface structures (LIPSS). It has been found that micrometer-scale grooving (produced, for example, using ultraprecision cutting) followed by short-pulsed laser irradiation can result in efficient LIPSS coverage of a large area. However, micrometer-scale grooves can remain on the surface after short-pulsed laser irradiation. In this paper, to clarify the phenomenon and processing principle of groove-assisted short-pulsed laser irradiation, a finite-difference time-domain simulation is developed and experiments are conducted using 304 stainless steel and nickel-phosphorus (Ni–P) plating layer substrates. The use of magnetic abrasive finishing (MAF) is proposed for fabricating sub-micrometer-deep straight grooves with various peak-to-peak distances (pitch length) prior to the short-pulsed-laser irradiation. The subsequent short-pulsed-laser irradiation produces sub-micrometer-deep straight structures superimposed on the MAF-produced surface. While the pattern and depth of LIPSS are influenced by the groove depth made by MAF prior to the short-pulsed laser irradiation, the pitch length of LIPSS is dependent on the laser wavelength. This demonstrates the ability of MAF to produce grooves that guide the LIPSS and the efficacy of the developed method for fabricating fine LIPSS. The geometry of the sub-micrometer deep grooves—made prior to the short-pulsed laser irradiation—is the dominant factor in determining the pattern and geometry of the LIPSS.
关键词： Straight sub-micrometer groove,Surface roughness,Magnetic abrasive finishing,Short-pulsed laser
更新于2025-09-12 10:27:22
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Space–time Galerkin methods for simulation of laser heating using the generalized nonlinear model
摘要： The generalized thermal model is a thermodynamically consistent extension of the classical Fourier’s law for describing thermal energy transportation which is very relevant to applications involving very small length, time scales and/or at extremely low temperatures. Under such conditions, thermal propagation has been observed to manifest as waves, a phenomenon widely referred to as second sound effect. However, this is in contrast to the paradoxical prediction of the Fourier’s model that thermal disturbances propagate with infinite speed. In this work, we review the nonlinear model based on the theory of Green and Naghdi for thermal conduction in rigid bodies and present its implementation within a class of space–time methods. The unconditional stability of the time-discontinuous Galerkin method without restriction over the grid structure of the space–time domain is proved. We also perform a number of numerical experiments to study the convergence properties and analyze the thermal response of materials under short-pulsed laser heating in two space dimensions.
关键词： Fourier’s law,Generalized thermal model,Time-discontinuous Galerkin method,Second sound,Short-pulsed laser
更新于2025-09-12 10:27:22
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[Laser Institute of America ICALEO? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18–22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Comparison between ps- and μs-laser radiation for drilling holes for force transmission elements in CFRP-preforms
摘要： Current lightweight strategies in automobile, aerospace and wind energy applications include composite structures consisting of metal and fiber reinforced plastics for minimum weight, maximum force transmission and high material efficiency. Therefore, economic and technological beneficial material processing for the integration of force transmission elements such as inserts are crucial for these high performance materials. Current state of the art of machining carbon fiber reinforced material is to drill or mill the work piece after the consolidation process. Conventional mechanical and water jet processes lead to high tool wear and often non-repairable defects in the work piece such as delamination, fiber pullout, cracks in matrix and fibers, and deformation. Laser processing of the consolidated material can prevent force induced defects but leads to degradation of the matrix and leaves freestanding fibers inside the drilling hole which can damage the protective surface of subsequently inserted force transmission elements. This is especially critical for lifetime and performance during operation of the structural part. One solution is to drill the so called preform, prior to the infusion process, insert force transmission elements and subsequently infuse the preform with resin. Ultra sonic excited cutting knifes are not applicable for cutting hole diameters of a few millimeters with high aspect ratios. Punching as well as water jet cutting drop out due to force induced interaction with the textile or necessity of a subsequent drying process. Laser material processing could be an adequate solution to circumvent the above mentioned issues. Within this work, non-crimp carbon fiber (NCF) layers are investigated regarding laser processing via ultra-short pulsed and microsecond (fiber laser) radiation. The influence of different process parameters such as scanning speed, repetition rate and laser power are being evaluated regarding geometrical and materialographical quality such as conicity, textile swelling and heat affected zone (HAZ). The temperature distribution during laser processing is important for the estimation of when and where the knitting yarn, which keeps the carbon fiber plies together, disintegrates. Without the knitting yarn swelling occurs which is not desired for subsequent process steps.
关键词： force transmission elements,CFRP-preforms,microsecond laser,ultra-short pulsed laser,laser drilling
更新于2025-09-11 14:15:04
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A review on glass welding by ultra-short laser pulses
摘要： Glass welding by ultra-short pulsed lasers is a piece of technology that offers high strength joints with hermetic sealing. The joints are typically formed in glass that is transparent to the laser by exploiting nonlinear absorption effects that occur under extreme conditions. Though the temperature reached during the process is on the order of a few 1000 °C, the heat affected zone (HAZ) is confined to only tens of micrometers. It is this controlled confinement of the HAZ during the joining process that makes this technology so appealing to a multitude of applications because it allows the foregoing of a subsequent tempering step that is typically essential in other glass joining techniques, thus making it possible to effectively join highly heat sensitive components. In this work we give an overview on the process, development and applications of glass welding by ultra-short pulsed lasers.
关键词： ultra-short pulsed laser processing,glass joining,USP glass welding,brittle materials
更新于2025-09-11 14:15:04