[Show abstract][Hide abstract] ABSTRACT: Characteristics of shock wave as well as its evolution of aluminum
plasma produced by nanosecond YAG laser is investigated by time-resolved
optical shadowgraph images. Experimental results show that shock wave is
strongly influenced by the laser parameters and target arrangement.
Shock waves from aluminum plasma and air plasma are observed
simultaneously by shadowgraphs when the distance from lens to target
surface (DLTS) is longer than the lens focal length, and a narrow bright
"line" is observed in the region where shock waves from Al plasma and
air plasma meet. The longitudinal expansion velocity of shock wave from
Al plasma is largely influenced by DLTS and laser intensity as well, and
it increases with laser intensity at the early stage of plasma expansion
and reach to a maximum of 8.1×104 m/s.
No preview · Article · May 2013 · Proceedings of SPIE - The International Society for Optical Engineering
[Show abstract][Hide abstract] ABSTRACT: Nano- and microscale structures on a material surface formed by femtosecond laser processing have greatly changed optical characteristics, wettability, as well as other properties of the material. In this work, we report the formation of nano- and microscale structures on a spherical Al surface with femtosecond laser filament, and find that the filament-processed surface has a strong light-trapping ability from UV to IR (0.2–2.5 μm). Our result demonstrates that this method can be used to process a spherical surface without the complexity of a 4-axis sample control, and in principle, it is applicable to any non-planar sample.
No preview · Article · May 2012 · Applied Physics Letters
[Show abstract][Hide abstract] ABSTRACT: The abilities to trigger and guide high-voltage discharge by using single and multiple filaments (MFs) are experimentally studied. It is shown that the discharge voltage threshold can be reduced significantly in both regimes of single and MF; however, the MF does not gain a larger reduction than a single filament. This behavior of the MF is attributed to the single discharge path rather than simultaneous multiple ones as one might expect during the discharge process. (C) 2012 Optical Society of America