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Proceedings Paper

Femtosecond laser micromachining of technical materials
Author(s): Joern Bonse; Steffen Baudach; Joerg Krueger; Wolfgang Kautek
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Paper Abstract

Micromachining experiments were performed with Ti:sapphire laser pulses (130 fs - 150 fs, 800 nm, approximately 10 Hz) in air. Employing the direct focusing technique, highly absorbing titanium nitride (TiN) and weakly absorbing polyimide (PI) and polymethylmethacrylate (PMMA) served as target materials. The lateral and vertical precision of the laser ablation and morphological features were characterized by scanning force (SFM), scanning electron (SEM) and optical microscopy. For TiN, incubation can be observed, i.e. the single-pulse surface damage threshold (0.26 J/cm2) is by a factor of two greater than the threshold for 100 pulses. Ablation rates below 10 nm per pulse can be achieved. The evolution of sub-wavelength ripples is presented in dependence on pulse number and laser fluence, respectively. The incubation behavior of the polymers can be described by an accumulation model as for TiN. Experiments on PI with varying focal lengths result in the same modification thresholds. Different polarization states of light (linear, circular) lead to a variation of the ablation rate and to various morphological patterns in the ablation craters (wavelength ripples, cones). Swelling of PMMA occurred at fluences below the ablation threshold.

Paper Details

Date Published: 16 August 2000
PDF: 12 pages
Proc. SPIE 4065, High-Power Laser Ablation III, (16 August 2000); doi: 10.1117/12.407346
Show Author Affiliations
Joern Bonse, Federal Institute for Materials Research and Testing (Germany)
Steffen Baudach, Federal Institute for Materials Research and Testing (Germany)
Joerg Krueger, Federal Institute for Materials Research and Testing (Germany)
Wolfgang Kautek, Federal Institute for Materials Research and Testing (Germany)

Published in SPIE Proceedings Vol. 4065:
High-Power Laser Ablation III
Claude R. Phipps, Editor(s)

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