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Experimental study on direct fabrication of micro channel on fused silica by picosecond laser
摘要： Ultrafast laser ablation, known for its high precision and the depressed thermal influence during processing, is fevered in micro channel fabrication on the glass bulk. In present work, a micro channel structure fabricated on fused silica bulk by a picosecond pulsed laser is parametrically investigated with different processing environments, scanning velocities, pulse energies, hatch distances and repetitive scans. The best processing parameters are determined through the material remove rate and the bottom surface roughness of the channel. Moreover, the fabrication defect attributed to the heat accumulation effect is analyzed by Raman spectrum. A scanning strategy is put forward to compensate the asymmetry in the cross section of the micro channels.
关键词： Heat accumulation,Surface roughness,Scanning strategy,Micro channel,Picosecond laser
更新于2025-09-23 15:21:01
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One-Step Femtosecond Laser Stealth Dicing of Quartz
摘要： We report on a one-step method for cutting 250-μm-thick quartz plates using highly focused ultrashort laser pulses with a duration of 200 fs and a wavelength of 1030 nm. We show that the repetition rate, the scan speed, the pulse overlap and the pulse energy directly influence the cutting process and quality. Therefore, a suitable choice of these parameters was necessary to get single-pass stealth dicing with neat and flat cut edges. The mechanism behind the stealth dicing process was ascribed to tensile stresses generated by the relaxation of the compressive stresses originated in the laser beam focal volume during irradiation in the bulk material. Such stresses produced micro-fractures whose controlled propagation along the laser beam path led to cutting of the samples.
关键词： ultrashort laser pulses,stealth dicing,transparent materials,heat accumulation,quartz
更新于2025-09-23 15:19:57
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B36 Laser machining of glass
摘要： We present a numerical and experimental study on the microdrilling of glass with UV laser pulses with the repetition rates from 1 kHz to 20 kHz. Pulse repetition frequency dependency on ablation threshold at the surface of the glass was discussed experimentally and numerically. It was confirmed that the pulse repetition rate influenced heat accumulation and temperature of illuminated area changed.
关键词： heat accumulation,glass,Laser machining
更新于2025-09-19 17:13:59
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Laser cutting path optimization with minimum heat accumulation
摘要： A new approach for minimizing both cutting path and heat accumulation in laser cutting process is presented in this paper. The proposed algorithm was based on a memetic algorithm combining a powerful genetic algorithm with an adaptive large neighborhood search. The cutting path problem was modeled and solved in accordance with generalized traveling salesman problem. A heat conduction model was incorporated into the cutting path optimization by assigning a critical radius of heat-affected zone as a constraint. A penalty was given to the cutting paths overlapping the heat-affected zone to minimize the heat accumulation in workpiece. A heat map indicating thermal gradient around the laser piercing points was also presented together with the optimum cutting path to visualize the level of heat accumulation. By comparing to the approach without the heat constraint, the algorithm incorporating with the heat effect was capable of determining the laser cutting path with minimum travel distance and heat accumulation in workpiece. The presented method could further be applied for other thermal-related processes such as surface hardening, welding, and additive manufacturing, whose processing distance and heat issue need to be optimized for gaining their productivity and final product quality.
关键词： Laser cutting,GTSP,Heat accumulation,Memetic algorithm,Tool path
更新于2025-09-12 10:27:22
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Simulation of the dynamics of heat accumulation during in-volume modification with ultrashort laser pulses
摘要： Working with ultrashort pulsed (USP) laser systems with high repetition rates, heat accumulation effects evolve and subsequently the absorption becomes linear. As a consequence, the process dynamics change significantly. Structuring glasses with those USP Lasers leads to melted lines that are used for waveguides, welding or selective laser-induced etching whose resulting qualities are strongly depending of the structuring results and given smoothness. We perform simulations during in-volume modification processes, by recalculating the absorption behavior in between the iteration steps of heat accumulation. The simulation results provide explanations for smoothness or non-smoothness of modifications comparable to experiments in glass.
关键词： pulse-to-pulse simulation,heat accumulation,iterative simulation,high repetition ultrashort pulsed laser,in-volume modification,simulation of process dynamics
更新于2025-09-12 10:27:22
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Heat accumulation effects in laser processing of diamond-like nanocomposite films with bursts of femtosecond pulses
摘要： In this paper, we have investigated the burst mode (BM) ablation and surface structuring of diamondlike nanocomposite (DLN) a-C:H:Si:O films with femtosecond laser pulses (wavelength λ = 515 nm, pulse duration τ = 320 fs, and pulse repetition rate f = 100 kHz) under different scanning conditions (single spots and linear structures). The pulse separation in the bursts is 25 ns (intraburst frequency f = 40 MHz), and the pulse number is varied from 1 to 8. The ablation depth and specific ablation rates (μm3/μJ) are found to be higher for the burst mode compared to single-pulse irradiation, increasing with the pulse number in the burst. The obtained experimental data of the higher ablation efficiency are shown to correlate with computer simulations of the BM ablation. In correlation with the ablation findings, Raman spectra of single spots and microgrooves have evidenced a growing graphitization of the amorphous film structure with the pulse number in the bursts (at an equal energy deposited into the films). Contact-mode atomic force microscopy (AFM) is applied to reveal an influence of the BM processing on the surface properties (nanoscale relief, friction) of laser-structured films. Based on the ablation and Raman data analysis, AFM examination of ablated/redeposited layers, and computer simulations of the burst mode ablation, the heat accumulation is identified as the main factor responsible for the enhanced ablation efficiency during the BM processing of DLN films. In addition, results of the high precision surface microstructuring of DLN films in the burst mode are presented.
关键词： heat accumulation,diamondlike nanocomposite films,surface structuring,femtosecond laser pulses,burst mode ablation
更新于2025-09-12 10:27:22
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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - The role of pulse to pulse interactions during usp-laser ablation with high average power and repetition rates
摘要： Ultrafast lasers are a versatile tool for micro processing for a wide range of materials. One common field of application is e.g. the surface structuring for mold and embossing tools. While the extremely short pulse durations < 10 ps and interaction times enable highly precise processing quality, the productivity is one major issue and much too small for many industrial applications. To improve the productivity and throughput, increasing the applied average power is a key parameter. Therefore, ultrafast lasers with high average power have the potential to scale up the productivity and reduce the processing times significantly. We present investigations on the processing of metals with a multi-100 W ultrafast laser system with pulse repetition rates of up to 20 MHz. For such power levels and high repetition rates effects like heat accumulation and shielding by pulse-plume interactions occur and have to be taken into account. We describe the relevance and impact of process parameters like spatial pulse separation, repetition rate and pulse duration on the productivity of the ablation process. A theoretical model is presented to distinguish between the influences of the aforementioned effects on the experimental results. Moreover, the fabrication of surface structures utilizing multi-100 W average power is presented.
关键词： ultrafast lasers,repetition rates,heat accumulation,pulse-plume interactions,high average power,micro processing
更新于2025-09-11 14:15:04