Femtosecond laser ablation properties of borosilicate glass
- Mechanical Engineering Department, University of Texas at Austin, Austin, Texas 78712 (United States)
We study the femtosecond laser ablation properties of borosilicate glass using atomic force microscopy and laser pulses of 200 fs duration, centered at 780 nm wavelength. We show that both single-shot and multishot ablation threshold fluences can be determined by studying the diameter and the depth of single-shot ablated craters. The linear relationship between the square of the crater diameter and the logarithm of the laser fluence in the form of D{sup 2}=2w{sub 0}{sup 2}ln(F{sub 0}/F{sub th}{sup N=1}) provides the single-shot ablation threshold, F{sub th}{sup N=1}, whereas the linear relationship between the ablation depth and the logarithm of laser fluence in the form of h{sub a}={alpha}{sub eff}{sup -1}ln(F{sub 0}/F{sub th}{sup N>1}) provides the multishot ablation threshold, F{sub th}{sup N>1}. The results depict a multishot ablation threshold of {approx_equal}1.7 J/cm{sup 2} independent of the atmospheric conditions. The slopes of the linear fits also provide a precise estimate of the beam radius at the surface, w{sub 0}{approx_equal}5.9 {mu}m, and the ''effective optical penetration depth,'' {alpha}{sub eff}{sup -1}{approx_equal}238 nm in air. The method is systematic, provides results that are consistent with the literature, and eliminates uncertainties because of instrument sensitivities. We also show that threshold measurement based on the extrapolation of volume to zero, a method used often in previous studies, is somewhat questionable. Finally, the measured dimensions of ablated craters reveal that the ablation volume per unit input energy is about 1.3-1.5 {mu}m{sup 3}/{mu}J at an intermediate fluence regime of 10<F{sub 0}{sup av}<40 J/cm{sup 2}. This value represents an order of magnitude larger ablation efficiency when compared to the ablation of glass with nanosecond ultraviolet laser pulses.
- OSTI ID:
- 20662158
- Journal Information:
- Journal of Applied Physics, Vol. 96, Issue 9; Other Information: DOI: 10.1063/1.1787145; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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