Abstract

The effect of ns bursting on percussion drilling of metal is investigated experimentally and analytically, and compared with the efficiency and quality of drilling using single ns pulses. Key advantages are demonstrated, correlating well with the results from a thermal theoretical model. The 1064 nm bursts contain up to 14 pulses of various pulse widths and spacing, and at frequencies of tens of MHz within the burst. The individual pulses have pulse widths of 10 to 200 ns, and up to 12 kW peak power. Burst repetition frequency is single shot to 500 kHz.

© 2011 OSA

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References

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  1. J. F. Ready, Effects of High-Power Laser Radiation (Academic Press, 1971), pp. 79.
  2. R. E. Russo, “Laser ablation,” Appl. Spectrosc. 49(9), 14A–28A (1995).
  3. J. C. Miller and R. F. Hagland, Jr., eds., Laser Ablation and Desorption (Academic Press, 1998).
  4. B. C. Stuart, M. D. Feit, S. Herman, A. M. Rubenchik, B. W. Shore, and M. D. Perry, “Optical ablation by high-power short-pulse lasers,” J. Opt. Soc. Am. B 13(2), 459–468 (1996).
  5. D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–63 (2004).
  6. X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).
  7. B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).
  8. J. König, S. Nolte, and A. Tünnermann, “Plasma evolution during metal ablation with ultrashort laser pulses,” Opt. Express 13(26), 10597–10607 (2005).
    [PubMed]
  9. D. M. Karnakis, G. Rutterford, and M. R. H. Knowles, “High power DPSS laser micromachining of silicon and stainless steel,” Proceedings of the Third International WLT-Conference in Manufacturing, Munich (June 2005).
  10. H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored nanosecond pulses,” Proc. SPIE 6796, 67961G, 67961G-8 (2007).
  11. S. T. Hendow, S. A. Shakir, and J. M. Sousa, “MOPA fiber laser with controlled pulse width and peak power for optimizing micromachining applications,” Proc. SPIE 7584, 758417, 758417-6 (2010).
  12. P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).
  13. S. T. Hendow and S. A. Shakir, “Structuring materials with nanosecond laser pulses,” Opt. Express 18(10), 10188–10199 (2010).
    [PubMed]
  14. S. T. Hendow, P. T. Guerreiro, N. Schilling, and J. Rabe, “Pulse shape control of a MOPA fiber laser for marking of stainless steel and other materials,” M604, ICALEO Proceedings (2010).
  15. M. Rekow, R. Murison, T. Panarello, C. Dunsky, C. Dinkel, and S. Nikumb, “Application of a pulse programmable fiber laser to a broad range of micro-processing applications,” M603, ICALEO Proceedings (2010).
  16. H. Pantsar, T. Eisenbeis, M. Rekow, R. Murison, H. Herfurth, and S. Heinemann, “process optimization for improving drilling efficiency in WET solar cell manufacturing,” M1102, ICALEO Proceedings (2010).
  17. S. Hendow, “Influence of Peak Power and ns Pulse Duration on Micromachining,” in Fiber Laser Applications, OSA Technical Digest (CD) (Optical Society of America, 2011), paper FThC4.
  18. A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).
  19. B. R. Campbell, T. M. Lehecka, J. Thomas, and V. Semak, “A study of material removal rates using the double pulse format with nanosecond pulse laser on metals,” in Proceedings of ICLEO, paper 401 (2008).
  20. R Knappe, “Scaling ablation rate for picosecond lasers using burst-pulse micromachining,” ICALEO Proceedings, M602 (2010).
  21. S. T. Hendow, J. R. Salcedo, R. Romero, and P. T. Guerreiro, “Dynamic pulsing of a MOPA fiber laser for enhanced material processing,” Proc. SPIE 7914, 791405, 791405-6 (2011).
  22. A. Ganino, Korn and Theresa M. Korn, Mathematical Handbook for Scientists and Engineers (Dover Edition, 2000), pp. 119.
  23. B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

2011 (1)

S. T. Hendow, J. R. Salcedo, R. Romero, and P. T. Guerreiro, “Dynamic pulsing of a MOPA fiber laser for enhanced material processing,” Proc. SPIE 7914, 791405, 791405-6 (2011).

2010 (2)

S. T. Hendow and S. A. Shakir, “Structuring materials with nanosecond laser pulses,” Opt. Express 18(10), 10188–10199 (2010).
[PubMed]

S. T. Hendow, S. A. Shakir, and J. M. Sousa, “MOPA fiber laser with controlled pulse width and peak power for optimizing micromachining applications,” Proc. SPIE 7584, 758417, 758417-6 (2010).

2009 (1)

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

2007 (1)

H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored nanosecond pulses,” Proc. SPIE 6796, 67961G, 67961G-8 (2007).

2005 (5)

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

J. König, S. Nolte, and A. Tünnermann, “Plasma evolution during metal ablation with ultrashort laser pulses,” Opt. Express 13(26), 10597–10607 (2005).
[PubMed]

A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

2004 (1)

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–63 (2004).

1996 (1)

1995 (1)

Armas, M.

A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).

Banks, P. S.

A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).

Breitling, D.

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–63 (2004).

Campbell, E. M.

A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).

Cournoyer, A.

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

Dausinger, F.

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–63 (2004).

Deladurantaye, P.

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

Dodell, A.

A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).

Feit, M. D.

Forsman, A. C.

A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).

Gamaly, E. G.

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

Gay, D.

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

Greif, R.

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).

Guerreiro, P. T.

S. T. Hendow, J. R. Salcedo, R. Romero, and P. T. Guerreiro, “Dynamic pulsing of a MOPA fiber laser for enhanced material processing,” Proc. SPIE 7914, 791405, 791405-6 (2011).

Heinemann, S.

H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored nanosecond pulses,” Proc. SPIE 6796, 67961G, 67961G-8 (2007).

Hendow, S. T.

S. T. Hendow, J. R. Salcedo, R. Romero, and P. T. Guerreiro, “Dynamic pulsing of a MOPA fiber laser for enhanced material processing,” Proc. SPIE 7914, 791405, 791405-6 (2011).

S. T. Hendow and S. A. Shakir, “Structuring materials with nanosecond laser pulses,” Opt. Express 18(10), 10188–10199 (2010).
[PubMed]

S. T. Hendow, S. A. Shakir, and J. M. Sousa, “MOPA fiber laser with controlled pulse width and peak power for optimizing micromachining applications,” Proc. SPIE 7584, 758417, 758417-6 (2010).

Herfurth, H.

H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored nanosecond pulses,” Proc. SPIE 6796, 67961G, 67961G-8 (2007).

Herman, S.

König, J.

Labranche, B.

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

Lauterborn, T.

H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored nanosecond pulses,” Proc. SPIE 6796, 67961G, 67961G-8 (2007).

Levesque, M.

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

Luther-Davies, B.

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

Madsen, N. R.

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

Mao, X. I.

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).

Nolte, S.

Pantsar, H.

H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored nanosecond pulses,” Proc. SPIE 6796, 67961G, 67961G-8 (2007).

Patwa, R.

H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored nanosecond pulses,” Proc. SPIE 6796, 67961G, 67961G-8 (2007).

Perry, M. D.

A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).

B. C. Stuart, M. D. Feit, S. Herman, A. M. Rubenchik, B. W. Shore, and M. D. Perry, “Optical ablation by high-power short-pulse lasers,” J. Opt. Soc. Am. B 13(2), 459–468 (1996).

Rode, A. V.

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

Romero, R.

S. T. Hendow, J. R. Salcedo, R. Romero, and P. T. Guerreiro, “Dynamic pulsing of a MOPA fiber laser for enhanced material processing,” Proc. SPIE 7914, 791405, 791405-6 (2011).

Roy, V.

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

Rubenchik, A. M.

Ruf, A.

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–63 (2004).

Russo, R.

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).

Russo, R. E.

Salcedo, J. R.

S. T. Hendow, J. R. Salcedo, R. Romero, and P. T. Guerreiro, “Dynamic pulsing of a MOPA fiber laser for enhanced material processing,” Proc. SPIE 7914, 791405, 791405-6 (2011).

Shakir, S. A.

S. T. Hendow and S. A. Shakir, “Structuring materials with nanosecond laser pulses,” Opt. Express 18(10), 10188–10199 (2010).
[PubMed]

S. T. Hendow, S. A. Shakir, and J. M. Sousa, “MOPA fiber laser with controlled pulse width and peak power for optimizing micromachining applications,” Proc. SPIE 7584, 758417, 758417-6 (2010).

Shore, B. W.

Sousa, J. M.

S. T. Hendow, S. A. Shakir, and J. M. Sousa, “MOPA fiber laser with controlled pulse width and peak power for optimizing micromachining applications,” Proc. SPIE 7584, 758417, 758417-6 (2010).

Stuart, B. C.

Taillon, Y.

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

Tünnermann, A.

Zeng, X.

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).

Appl. Phys., A Mater. Sci. Process. (1)

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).

Appl. Spectrosc. (1)

J. Appl. Phys. (1)

A. C. Forsman, P. S. Banks, M. D. Perry, E. M. Campbell, A. Dodell, and M. Armas, “Double pulse machining as a technique for the enhancement of material removal rates in laser machining of metals,” J. Appl. Phys. 98(3), 033302 (2005).

J. Opt. Soc. Am. B (1)

Opt. Eng. (2)

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).

Opt. Express (2)

Proc. SPIE (5)

H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored nanosecond pulses,” Proc. SPIE 6796, 67961G, 67961G-8 (2007).

S. T. Hendow, S. A. Shakir, and J. M. Sousa, “MOPA fiber laser with controlled pulse width and peak power for optimizing micromachining applications,” Proc. SPIE 7584, 758417, 758417-6 (2010).

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” Proc. SPIE 7195, 71951S, 71951S-12 (2009).

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–63 (2004).

S. T. Hendow, J. R. Salcedo, R. Romero, and P. T. Guerreiro, “Dynamic pulsing of a MOPA fiber laser for enhanced material processing,” Proc. SPIE 7914, 791405, 791405-6 (2011).

Other (10)

A. Ganino, Korn and Theresa M. Korn, Mathematical Handbook for Scientists and Engineers (Dover Edition, 2000), pp. 119.

J. F. Ready, Effects of High-Power Laser Radiation (Academic Press, 1971), pp. 79.

J. C. Miller and R. F. Hagland, Jr., eds., Laser Ablation and Desorption (Academic Press, 1998).

D. M. Karnakis, G. Rutterford, and M. R. H. Knowles, “High power DPSS laser micromachining of silicon and stainless steel,” Proceedings of the Third International WLT-Conference in Manufacturing, Munich (June 2005).

B. R. Campbell, T. M. Lehecka, J. Thomas, and V. Semak, “A study of material removal rates using the double pulse format with nanosecond pulse laser on metals,” in Proceedings of ICLEO, paper 401 (2008).

R Knappe, “Scaling ablation rate for picosecond lasers using burst-pulse micromachining,” ICALEO Proceedings, M602 (2010).

S. T. Hendow, P. T. Guerreiro, N. Schilling, and J. Rabe, “Pulse shape control of a MOPA fiber laser for marking of stainless steel and other materials,” M604, ICALEO Proceedings (2010).

M. Rekow, R. Murison, T. Panarello, C. Dunsky, C. Dinkel, and S. Nikumb, “Application of a pulse programmable fiber laser to a broad range of micro-processing applications,” M603, ICALEO Proceedings (2010).

H. Pantsar, T. Eisenbeis, M. Rekow, R. Murison, H. Herfurth, and S. Heinemann, “process optimization for improving drilling efficiency in WET solar cell manufacturing,” M1102, ICALEO Proceedings (2010).

S. Hendow, “Influence of Peak Power and ns Pulse Duration on Micromachining,” in Fiber Laser Applications, OSA Technical Digest (CD) (Optical Society of America, 2011), paper FThC4.

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Figures (8)

Fig. 1
Fig. 1

(a) Schematic of the fiber laser used in these tests. The seed laser and amplifier chain is controlled to form pulses of preconfigured peak power and energy. (b) MOPA-DY laser used in this test.

Fig. 2
Fig. 2

Two sample burst profiles. (a) A sample burst of 5 pulses of 20 ns wide each, and 60 ns period, giving an effective pulse frequency of 16.7 MHz. The laser is operated at burst repetition frequency of 490 KHz. (b) Sample 8-pulse burst of 10 ns pulses. Pulse spacing is arbitrarily set such that the leading edge is spaced at 40, 60, 80, 100, 120, 140 and 160 ns, respectively, giving an average pulse repetition frequency of 10 MHz. The burst repetition frequency for this sample is 100 KHz.

Fig. 3
Fig. 3

Schematic of the percussion drilling and pulse counting system. The focused spot is about 20 μm in diameter. The metal sheet used is 25 μm thick stainless steel. A detector is used under the drilled hole to identify penetration and interrupt the laser’s burst emission. An external counter records the number of bursts needed to drill through the metal sheet. The figure at the top-left shows the sample 5-pulse burst of Fig. 2(a), where each burst is externally triggered at T interval of 2040 ns, corresponding to the burst repetition frequency of 490 kHz.

Fig. 4
Fig. 4

(a) Temporal profile of a sequence of five incident pulses of various peak powers to be deposited on the surface of stainless steel substrate. All the pulses are set to have the same pulse energy of 10 μJ. Pulse widths are assumed to be 10, 20, 50, 100 and 200 ns, respectively. Pulse separation is 25 ns, and spot diameter on the surface is 50 μm. The transverse intensity profile is Gaussian. (b) Eq. (1) is used to calculate the temperature rise of the substrate on axis. The various traces correspond to the calculated temperatures of the surface (top trace), and at depths of 1, 2, 3, 4, 5, 6 and 7 μm below the surface. The lower level of the gray area corresponds to the melting point of steel, while the top level corresponds to its boiling point. Note that only the 10 ns pulse leads to surface temperature that exceeds the boiling threshold.

Fig. 5
Fig. 5

(a) The number of pulses required to drill clear holes in the stainless steel foil as a function of their pulse width and peak power. The vertical error bar for all the points is about 5% total, which corresponds to about one count, except for the 10 ns point, which is about five pulses. (b)-(d) SEM photos for percussion drilled holes. All three are drilled using pulses that are 100 ns wide, but with different fluence and irradiance levels. The scale at the bottom right of all photos is 100 μm.

Fig. 6
Fig. 6

(a) The total energy required to drill clear holes as a function of pulse width and peak power. (b)-(d) SEM photos for drilled holes using 2 KW of peak power, and for pulse widths of 30, 100, and 200 ns. Note that all three holes require the same total energy of 2 mJ to percussion drill through the foil. The scale at the bottom right is 100 μm for all photos. The vertical error bar for all the data points is about 5% total.

Fig. 7
Fig. 7

Sample SEM photos of percussion drilled holes performed using bursts of pulses of different pulse number and peak power. The top row shows photos of bursts for N = 2, 6 and 10 pulses. All the pulses are 30 ns wide, and all pulse spacing is 50 ns, corresponding to an effective frequency of about 12.5 MHz. All the photos shown in (a)-(c) are of the same magnification, and the scale shown at the bottom left of all photos is for a distance of 70 μm.

Fig. 8
Fig. 8

Correlation between experimental and theoretical results for the number of bursts required to drill through a thin metal sheet, while increasing N, the number of pulses per burst, and as peak power is adjusted. The pulse profiles and images of the drilled holes are shown in Fig. 7. The theoretical results are generated using the analytical model of section 7.

Equations (4)

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Δ T ( r , z , t ) = I max γ κ π K 0 t g ( t t ' ) t ' [ 1 + 8 κ t ' w 2 ] e [ z 2 4 κ t ' + r 2 4 κ t ' + 0.5 w 2 ] d t '
Δ T 1 ( r , z , τ ) = 2 γ E o C p ρ 0.5 π 3 κ τ ( w 2 + 4 κ τ ) e [ z 2 2 κ τ + 2 r 2 w 2 + 4 κ τ ]
h [ 2 κ τ ln { ( π / 2 ) 3 / 2 Δ T B κ τ C p ρ ( w 2 + 4 κ τ ) γ E o } ] 1 / 2
N B u r s t s = H h N

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