Ultra-short pulse lasers

Ultra-short pulsed laser processing Variable wavelength laser processing Cluster beam processing... 

In what follows, the laser damage characteristics are discussed when both alternating current electric fields and ultra-short pulse lasers are simultaneously applied to the dielectric materials. It is true that very high electric fields may allow the electron to reach an energy level sufficient to ionize, causing the impact ionization. As discussed earlier, the damage... 

Oh, Y.M., Lee, S. H., Park, S., Lee, J.S. (2004) A Numerical Study on Ultra-short Pulse Laser-induced Damage on Dielectrics Using the Fokker-Plank Equation, Int. J. Heat Mass Transfer, to appear. 

Besides the use in F2 and F2 immersion lithography, fluoropolymers are used in various fields. Fluoropolymer is one of the candidate for a polymer for MEMS, and fabrication of fluoropolymers by ultra-short pulsed lasers (9), and synchrotron radiations (10) has been studied. Polymer outgassing as well as the micro- and nano-fabrication depends on the polymer radiolysis. It is important for the micro- and nano-fabrication to investigate outgassing characteristics which is obvious outcome in the polymer radiolysis. 

Transparent colored YAG ceramics doped with Ti and Zr ions as possible broad-band materials for tunable and ultra-short pulses lasers were obtained. The procedure of doped ceramics fabrication included chemical co-precipitation, precursors heat treatment, YAG powder grinding, high pressure colloidal slip-casting for nanopowders compaction and vacuum sintering of performs at 1730-1800 C. Absorption spectra of Zr ceramics samples are similar to the spectra of correspondingly doped YAG single crystals. Zr luminescence was observed for the first time. Possibility to obtain laser action is discussed. 

Dausinger F (2004) Prasisionsbohren mil kxffzen xmd ultrakurzen laserpulsen (Laser drilling using short and ultra-short pulsed laser systems). Laser Technik j 1 40-44... 

Figure 3.13 Temporalcharacteristic of laser output intensity (a) fora single-modeCW laser (b) fora random multi-modeCW laser (c) for a mode-locked ultra-short pulse laser...

A Class 3B laser poses hazards when eyes receive direct exposures. Diffuse reflections such as from paper or other matte surfaces are not harmful. Continuous lasers in the wavelength range from 315 nm to far infrared must be limited to 0.5 W. For pulsed lasers between 400 and 700 nm, the limit is 30 mJ. Other limits apply to other wavelengths and to ultra-short pulsed lasers. Protective eyewear is typically required where direct viewing of a class 3B laser beam may occur. Class 3B lasers must be equipped with a key switch and a safety interlock. 

STRUCTURING OF METAL SURFACES BY ULTRA-SHORT PULSED LASER IRRADIATION... 

For ultra-short pulsed laser irradiation of metals, with pulse duration smaller than 1 ps, two different ablation regimes, termed gentle and strong ablation, are observed (Nolte et al., 1997). At laser fluences (laser pulse energy per unit area) just above the ablation threshold, the average ablation rate is determined by the optical penetration depth (for example, 13 nm for copper) of laser radiation in metal. The average ablation rate is low. The processed area is relatively smooth with nanometer-sized... 

Table 3 Quantitative Characterization of Superhydrophobic Metal Surfaces Structured by Ultra-Short Pulsed Laser Irradiation Structure...

The results of the quantitative characterization of superhydrophobic metal surfaces structured by ultra-short pulsed laser irradiation are summarized in Table 3. The water contact angles measured prior to the laser irradiation were 65°—85° on copper, titanium, iron, and aluminum... 

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