<p>This work examines the thermal effects in ultrashort pulse laser micromachining of graphite at high repetition rates through a combination of experimental and numerical approaches. While several studies have explored heat accumulation in similar contexts, the integration of real-time thermal measurements with complementary simulations remains limited. Experiments were performed using a 1030 nm, 300 fs laser operating at repetition rates between 0.333 MHz and 2 MHz with varying scanning speeds (1-120 mm/s). Temperature distributions were monitored using a thermal camera to analyze heat accumulation, crater formation, and the heat-affected zone. Two numerical models were developed to study the laser-matter interaction. The two-temperature model resolves the ultrafast electron-lattice dynamics, providing insights into the ablation threshold (0.2 J/cm<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="339_2025_8642_Article_IEq1.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="8" /> </InlineMediaObject> <EquationSource Format="TEX">$^2$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>2</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>) and material removal process. The continuous-wave model approximates cumulative heating effects and enables the evaluation of temperature rise and spatial thermal gradients under quasi-continuous conditions. Temperature gradients with characteristic lengths of approximately 50-250 <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="339_2025_8642_Article_IEq2.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">$\mu $</EquationSource> <EquationSource Format="MATHML"><math> <mi>μ</mi> </math></EquationSource> </InlineEquation>m were measured and reproduced by simulations. Comparisons between simulations and experimental results show good agreement, validating the ability of models to predict both transient and cumulative thermal behavior. The proposed approach provides a reliable framework for understanding thermal effects in laser micromachining of graphite and can be extended to other materials requiring precise thermal management.</p>

Assessment of thermal effects in laser micro-machining of graphite with ultrashort pulses at high repetition rate

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2025年6月6日

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C.E. Cifuentes Quintal,
T. Doualle,
Y. Pontillon,
J. L. Rullier,
L. Gallais

摘要

This work examines the thermal effects in ultrashort pulse laser micromachining of graphite at high repetition rates through a combination of experimental and numerical approaches. While several studies have explored heat accumulation in similar contexts, the integration of real-time thermal measurements with complementary simulations remains limited. Experiments were performed using a 1030 nm, 300 fs laser operating at repetition rates between 0.333 MHz and 2 MHz with varying scanning speeds (1-120 mm/s). Temperature distributions were monitored using a thermal camera to analyze heat accumulation, crater formation, and the heat-affected zone. Two numerical models were developed to study the laser-matter interaction. The two-temperature model resolves the ultrafast electron-lattice dynamics, providing insights into the ablation threshold (0.2 J/cm $^2$ $^{2}$ ) and material removal process. The continuous-wave model approximates cumulative heating effects and enables the evaluation of temperature rise and spatial thermal gradients under quasi-continuous conditions. Temperature gradients with characteristic lengths of approximately 50-250 $\mu $ $μ$ m were measured and reproduced by simulations. Comparisons between simulations and experimental results show good agreement, validating the ability of models to predict both transient and cumulative thermal behavior. The proposed approach provides a reliable framework for understanding thermal effects in laser micromachining of graphite and can be extended to other materials requiring precise thermal management.