The effect of standing acoustic waves on the formation of laser-induced air plasmas.

The expected location of an air plasma produced by a focused YAG laser pulse has been found to be influenced by the acoustics of the surrounding environment. In open air, the expected location of a laser-induced air plasma is centered close to the focal point of the lens focusing the laser beam. When confining the same beam coaxially along the interior of a quartz tube, the expected location of the air plasma shifts away from the focal point, toward the focusing lens, in a region of less laser fluence.

Utilization of the coherence function with Welch's method for signal analysis in low resolution laser-induced breakdown spectroscopy.

This work presents a technique by which a low resolution ( approximately 1 nm) fiberoptic spectrometer may be used to definitively identify elements and molecular fragments in laser-induced breakdown spectroscopy. Commercial laser-induced breakdown spectroscopy (LIBS) spectrometers have high resolution in the area of spectral interest, and software is used to identify elements via a look-up table containing known spectral lines. When analyzing spectra from a lower resolution fiber-optic spectrometer, software based on look-up tables can produce erroneous results, reporting elements absent from the sample.