L. H. GAABOUR ET AL.
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[6] A. Takita and Y. Hayasaki, “Dynamics of Femtosecond
Laser-Induced Breakdown in Water,” Proceedings of
SPIE, Vol. 7201, 2009.
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0
1
2
0
1
2
(1) 6 ns
(2) 30 ps
(3) 100 fs
1064nm
Pth(MW)
Focal leng th (c
6ns
30ps
100fs
m)
(3)
(2)
(1)
[7] J. Zhou, J. K. Chen and Y. Zhang, “Numerical Modeling
of Transient Progression of Plasma Formation in Biol-
ogical Tissues Induced by Short Laser Pulses,” Applied
Physics B: Lasers and Optics, Vol. 90, No. 1, 2008, pp.
141-148. doi:10.1007/s00340-007-2843-z
[8] A. Sollier, L. Berthe and R. Fabbro, “Numerical Mo-
deling of the Transmission of Breakdown Plasma Gene-
rated in Water during Laser Shock Processing,” European
Physical Journal Applied Physics, Vol. 16, 2001, pp. 131-
139.
Figure 7. Threshold power versus focal length for (1) 6 ns,
(2) 30 ps, and (3) 100 fs.
[9] D. X. Hammer, R. J. Thomas, G. D. Noojin, B. A. Rock-
well, P. K. Kennedy and W. P. Roach, “Experimental In-
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focal volume. The beam waist is assumed to vary along
the axial distance. The results of these calculations re-
vealed deep understanding about the temporal evolution
and spatial distribution of the free electron in the focal
volume. The highest electron density is obtained at the
centre focal point (z0, r0). The maximum volume of the
plasma is determined from the electron density distribu-
tion along the axial and radial distances and its value
showed an increase with increasing the laser pulse. More-
over, the shape of the formed plasma varies with the laser
pulse length. In addition, investigation of the effect of
self focusing over the studied pulse length indicated that
this process may play important role only for the femto-
second pulses when a focusing lens is used with focal
length ≥8.0 cm. No evidence of this effect is observed at
30 ps and 6 ns pulse lengths. Accordingly, laser sources
operating at the later pulse lengths as well as 100 fs pul-
ses focused with a lens of focal length less than 8.0 cm
can be used safely for ophthalmic microsurgery.
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