Pulse duration and energy density influence on laser processing of metals with short and ultrashort pulses

Influence of pulse duration on microprocessing of Al is studied. Results show noticeable differences in terms of quality, burr height and remolten or recast matter into micromachined grooves at high fluence regime for 120fs and 4,5 ps pulse duration. At 120 fs experimental results of penetration depth are found to be 2 or 3 times higher than the theoretical optical penetration depth and is lowered to this value with increasing pulse duration. At high fluence regime up to 2 J/cm2, ablation thresholds are found to be in the range 10 times higher than for the case of 1 J/cm2. Penetration depths are higher by a factor 10 to 20 than the theoretical optical penetration depth. The ablation rate is nearly constant until 1 ps and then falls down to 2 times lower values and decreases regularly until 4,5 ps. This time is supposed to correspond to a critical pulse width between ultrashort and short regime.

[1]  B. Rethfeld,et al.  Femtosecond laser-induced heating of electron gas in aluminium , 1999 .

[2]  Andreas Ruf,et al.  Modeling and investigation of melt ejection dynamics for laser drilling with short pulses , 2003, International Congress on Laser Advanced Materials Processing.

[3]  X Zhu,et al.  A new method for determining critical pulse width in laser material processing , 2000 .

[4]  Jean-Philippe Colombier,et al.  Hydrodynamic simulation of the ablation of metals by femtosecond laser pulses , 2004, SPIE High-Power Laser Ablation.

[5]  Friedrich Dausinger,et al.  Surface structuring of metals with short and ultrashort laser pulses , 2003, International Symposium on Laser Precision Microfabrication.

[6]  Friedrich Dausinger,et al.  Femtosecond technology for precision manufacturing: fundamental and technical aspects , 2003 .

[7]  P ? ? ? ? ? ? ? % ? ? ? ? , 1991 .

[8]  N. N. Nedialkov,et al.  Ablation of metals by ultrashort laser pulses , 2004, International School on Quantum Electronics: Laser Physics and Applications.

[9]  李幼升,et al.  Ph , 1989 .

[10]  M. Stuke,et al.  Sub-picosecond UV laser ablation of metals , 1995 .

[11]  Andreas Ostendorf,et al.  Micromachining of Metals Using Ultrashort Laser Pulses , 1999 .

[12]  C. Donnet,et al.  New methods to control quality and precision of micro-machining with femtosecond lasers , 2003, International Symposium on Laser Precision Microfabrication.

[13]  Marc Sentis,et al.  Modeling of metal ablation induced by ultrashort laser pulses , 2004 .

[14]  Mohamed Chaker,et al.  Ablation of aluminum thin films by ultrashort laser pulses , 2001 .

[15]  R. More,et al.  An electron conductivity model for dense plasmas , 1984 .

[16]  Krzysztof A. Nowakowski,et al.  Laser beam interaction with materials for microscale applications , 2005 .

[17]  M. Chaker,et al.  Critical-point phase separation in laser ablation of conductors. , 2001, Physical review letters.

[19]  Eric Audouard,et al.  Comparison of heat-affected zones due to nanosecond and femtosecond laser pulses using transmission electronic microscopy , 2002 .

[20]  Andreas Ruf,et al.  Fundamental aspects in machining of metals with short and ultrashort laser pulses , 2004, SPIE LASE.

[21]  G. Mourou,et al.  Laser ablation and micromachining with ultrashort laser pulses , 1997 .

[22]  Juergen Jandeleit,et al.  Picosecond laser ablation of thin copper films , 1996 .

[23]  A. Luft,et al.  A study of thermal and mechanical effects on materials induced by pulsed laser drilling , 1996 .

[24]  P. A. Atanasov,et al.  Ablation of metals by ultrashort laser pulses , 2004 .