Delocalized Photomechanical Effects of UV ns Laser Ablation on Polymer Substrates Captured by Optical Holography Workstation: An Overview on Experimental Result
A brief overview of results from an experimental investigation performed on polymer materials to examine delocalized photomechanical effects generated due to UV laser ablation is provided. Delocalized structural modifications were observed in PMMA, PS by means of optical holographic interferometry. The integrity of samples was examined before and after irradiation in 193 and 248？nm (15？ns) above and below ablation threshold, F = 0.1–1.0？J/cm2. A value of structural continuity was initially determined for each sample by generation of a reference holographic image before irradiation. Microscopic discontinuities were intentionally induced to act as preexistent defects. Sequential holographic recording monitored the growth of morphological alterations according to the number of pulses in the neighbor as well as far from the preexistent discontinuities. The imposed alterations are visually observable at the whole extent of the irradiated sample in distances far off the ablation spot as local cracks and voids. The induced flaws cannot be classified as transient or instantly generated. Fracture follows a long-term emergence and deterioration pattern. Extensively fluctuated long-term effects were also observed in laser-assisted varnish removal of multilayered technical samples simulating Byzantine icons with decrease of effect duration and fluctuation being according to increase in sample homogeneity. 1. Introduction Irradiation of solid organic material with pulsed ultraviolet laser light of intense power density leads to cold etching or ablative photodecomposition (APD) of the substrate. The APD effect located in the limited region of the laser spot is attributed to local photochemical mechanism causing discrete ejection of target material without altering the adjacent bulk which allows for controlled substrate processing conveniently suited for many applications. The mass ejection and the expansion of high-density plasma though induce a mechanical effect characterized by a recoil pressure and a shock wave propagating inside the solid. The photomechanical effects in contrast to the presented study are mainly reported in literature in concern to the physical processes in the ablated region as influence of pressure versus time. Specifically, laser ablation using 193, 248？nm excimer laser radiation is commonly used [1–12] in microelectronic industry for etching of polymer substrates and in medical applications for controlled excision of tissue as well as in ophthalmology and in photorefractive surgery for restoring of myopia and has been proved to be a highly
References
[1]
D. B？uerle, Laser Processing and Chemistry, Springer, Berlin, Germany, 2000.
[2]
D. Bauerle, Laser Processing and Chemistry, Springer, Berlin, Germany, 3rd edition, 2011.
[3]
D. J. Krajnovich and J. E. Xazquez, “Formation of “intrinsic” surface defects during 248 nm photoablation of polyimide,” Journal of Applied Physics, vol. 73, p. 3001, 1993.
[4]
J.-F. Silvain, H. Niino, S. Ono, S. Nakaoka, and A. Yabe, “Surface modification of elastomer/carbon composite by Nd+:YAG laser and KrF excimer laser ablation,” Applied Surface Science, vol. 141, no. 1-2, pp. 25–34, 1999.
[5]
B. Hopp, M. Csete, K. Revesz, J. Vinko, and Z. Bor, “Formation of the surface structure of polyethylene-terephtalate (PET) due to ArF excimer laser ablation,” Applied Surface Science, vol. 96, pp. 611–616, 1996.
[6]
F. Wagner and P. Hoffmann, “Structure formation in excimer laser ablation of stretched poly(ethylene therephthalate) (PET): the influence of scanning ablation,” Applied Physics A, vol. 69, no. 1, supplement, pp. S841–S844, 1999.
[7]
J. Heitz, E. Arenholz, D. B？uerle, H. Hibst, A. Hagemeyer, and G. Cox, “Dendritic surface structures on excimer-laser irradiated PET foils,” Applied Physics A Solids and Surfaces, vol. 56, no. 4, pp. 329–333, 1993.
[8]
S. Watanabe, T. J. Flotte, D. J. McAuliffe, and S. L. Jacques, “Putative photoacoustic damage in skin induced by pulsed ArF excimer laser,” Journal of Investigative Dermatology, vol. 90, no. 5, pp. 761–766, 1988.
[9]
A. G. Doukas, D. J. McAuliffe, and T. J. Flotte, “Biological effects of laser-induced shock waves: structural and functional cell damage in vitro,” Ultrasound in Medicine and Biology, vol. 19, no. 2, pp. 137–146, 1993.
[10]
in 9th annual Laser-Tissue Interaction Conference, S. L. Jacques, Ed., vol. 3254 of Proceedings of SPIE, Washington, DC, USA, 1998.
[11]
C. B. Gabrieli, E. Pacella, S. Abdolrahimzadeh, F. Regine, and R. Mollo, “Excimer laser photorefractive keratectomy for high myopia and myopic astigmatism,” Ophthalmic Surgery and Lasers, vol. 30, no. 6, pp. 442–448, 1999.
[12]
R. A. Lindley, R. M. Gilgenbach, C. H. Ching, J. S. Lash, and G. L. Doll, “Resonant holographic interferometry measurements of laser ablation plumes in vacuum, gas, and plasma environments,” Journal of Applied Physics, vol. 76, no. 9, pp. 5457–5472, 1994.
[13]
S. Georgiou, V. Zafiropulos, D. Anglos, C. Balas, V. Tornari, and C. Fotakis, “Excimer laser restoration of painted artworks: procedures, mechanisms and effects,” Applied Surface Science, vol. 127–129, pp. 738–745, 1998.
[14]
V. Tornari, D. Fantidou, V. Zafiropulos, N. A. Vainos, and C. Fotakis, “Photomechanical effects of laser cleaning: a long-term non-destructive holographic interferometric investigation on painted artworks,” in 3rd International Conference on: Vibration Measurements by Laser Techniques: Advances and Applications, vol. 3411 of Proceedings of SPIE, pp. 420–430, June 1998.
[15]
I.-Y. S. Lee, X. Wen, W. A. Tolbert, D. D. Dlott, M. Doxtader, and D. R. Arnold, “Direct measurement of polymer temperature during laser ablation using a molecular thermometer,” Journal of Applied Physics, vol. 72, no. 6, pp. 2440–2448, 1992.
[16]
A. D. Zweig, V. Venugopalan, and T. F. Deutsch, “Stress generated in polyimide by excimer-laser irradiation,” Journal of Applied Physics, vol. 74, no. 6, pp. 4181–4189, 1993.
[17]
S. Siano, R. Pini, and R. Salimbeni, “Variable energy blast modeling of the stress generation associated with laser ablation,” Applied Physics Letters, vol. 74, no. 9, pp. 1233–1235, 1999.
[18]
K. J. G？svik, Optical Metrology, Wiley, New York, NY, USA, 2nd edition, 1995.
[19]
C. H. Vest, Holographic Interferometry, Academic, New York, NY, USA, 1971.
[20]
R. A. Lindley, R. M. Gilgenbach, and C. H. Ching, “Resonant holographic interferometry of laser-ablation plumes,” Applied Physics Letters, vol. 63, no. 7, pp. 888–890, 1993.
[21]
M. Olfert and W. W. Duley, “Holographic interferometry of isotherms during laser drilling of fused quartz,” Journal of Physics D: Applied Physics, vol. 29, no. 5, pp. 1140–1145, 1996.
[22]
A. Kreuttner, B. Lau, A. Mann et al., “Holographic interferometry for the display of shock wave induced deformations and vibrations—A contribution to laser lithotripsy,” Lasers in Medical Science, vol. 8, no. 3, pp. 211–220, 1993.
[23]
I.-Y. S. Lee, W. A. Tolbert, D. D. Dlott et al., Journal of Imaging Science and Technology, vol. 36, p. 180, 1992.
[24]
F. C. Burns and S. R. Cain, “The effect of pulse repetition rate on laser ablation of polyimide and polymethylmethacrylate-based polymers,” Journal of Physics D: Applied Physics, vol. 29, no. 5, pp. 1349–1355, 1996.
[25]
W. D. Callister, Materials Science and Engineering : An Introduction, John Wiley & Sons, New York, NY, USA, 1997.
[26]
J. W. Smith, E. J. Kramer, and P. J. Mills, “Tailored adhesion at polymer/nonpolymer interfaces,” Journal of Polymer Science, Part B: Polymer Physics, vol. 32, no. 10, pp. 1731–1744, 1994.
[27]
M. Lokhandwalla and B. Sturtevant, “Fracture mechanics model of stone comminution in ESWL and implications for tissue damage,” Physics in Medicine and Biology, vol. 45, no. 7, pp. 1923–1940, 2000.
[28]
D. Blanchard, R. Casalengo, M. Pierre, and H. P. Trommsdorff, “Impulsive generation of hypersonic waves: an application to the measurement of acoustic properties of poly‐methyl‐methacrylate,” Journal of Applied Physics, vol. 65, no. 9, article 3351, 1989.
[29]
M. Centurion, Y. Pu, Z. Liu, D. Psaltis, and T. W. H？nsch, “Holographic recording of laser-induced plasma,” Optics Letters, vol. 29, no. 7, pp. 772–774, 2004.
[30]
J. R. Asay, D. L. Lamberson, and A. H. Guenther, “Pressure and temperature dependence of the acoustic velocities in polymethylmethacrylate,” Journal of Applied Physics, vol. 40, no. 4, pp. 1768–1783, 1969.
[31]
M. Jie and C. Y. Tang, “Limitation on crack speed for a strip-craze model applied to PMMA,” Theoretical and Applied Fracture Mechanics, vol. 34, no. 1, pp. 11–16, 2000.
[32]
S. Wu, Polymer Interface and Adhesion, Marcel Dekker, New York, NY, USA, 1982.
[33]
A. Bonarou, L. Antonucci, V. Tornari, S. Georgiou, and C. Fotakis, “Holographic interferometry for the structural diagnostics of UV laser ablation of polymer substrates,” Applied Physics A: Materials Science and Processing, vol. 73, no. 5, pp. 647–651, 2001.
[34]
A. Athanassiou, K. Lakiotaki, V. Tornari, S. Georgiou, and C. Fotakis, “Photocontrolled mechanical phenomena in photochromic doped polymeric systems,” Applied Physics A: Materials Science and Processing, vol. 76, no. 1, pp. 97–100, 2003.
[35]
V. Tornari, D. Fantidou, V. Zafiropulos, N. A. Vainos, and C. Fotakis, “Photomechanical effects of laser cleaning: a long-term non-destructive holographic interferometric investigation on painted artworks,” in 3rd International Conference on: Vibration Measurements by Laser Techniques: Advances and Applications, E. P. Tomasini, Ed., vol. 3411 of Proceedings of the SPIE, pp. 420–430, Ancona, Italy, June 1998.
