Fs-Time Resolved Microscopy as a tool for monitoring laser-matter interaction
Abstract
Femtosecond laser pulses provides the advantage in comparison with longer pulses that there is no interaction between laser and plasma. Moreover, the applied energy is deposited in much less time than nanosecond pulses, for example, which implies that plasma related phenomena will take place at different time scales, and present different ablation characteristics. We present a tool for monitoring laser-matter interaction using femtosecond pulses and a explanation of the related phenomena for improving plasma analysis.
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Fs-Time Resolved Microscopy as a tool for monitoring laser-matter interaction Irene M. Carrasco García Laboratorio Láser Dpto. Química Analítica Universidad de Málaga
Antecedents: Shadowgraphy Time resolved microscopy applied below and slightly above the ablation threshold Russo et al. Appl. Phys. A 69 (Suppl.) S887-S894 (1999) Von der Linde et al. Appl. Sur. Sci. 154-155 1-10 (2000)
Ti:Sa Laser Experimental set up
0 ps 50 ps 200 ps 500 ps ∞ 50 µJ 75 µJ 150 µJ Temporal evolution vs. Energy
0 fs 100 fs 200 fs 1 ps 20 ps 100 ps 200 ps ∞ The earliest stages of fs laser-matter interaction
Gaussian profile: Not all the irradiated target area receives the same fluence Different effects on targets according to the profile simmetry
Interferences are produced by wave superposition, reflected between the molten layer and the rarefaction wave (ablation front). As the system presents radial simmetry due to the pump beam profile, the fringe pattern produced by the laser-matter interaction with the system with the probe beam will be Newton rings Dynamic Newton rings
Rarefaction wave Bulk-molten layer interface Wave superposition Air (n =1) Shock wave front (n>1) n≈2
Rarefaction wave Bulk-molten layer interface Wave superposition Air (n =1) Shock wave front (n>1) n≈2