ABSTRACT
A nonresonant cavity ringdown diagnostic to measure light attenuation from atmospheric particulate matter at 532- and 355-nm wavelengths is described. The presence of atmospheric particulate is clearly detectable with this technique, as demonstrated by experimental results. The extinction cross section is higher at 355 than at 532 nm, although we were able to purchase significantly higher-reflectivity optics at 532 nm. The expected advantage at 355 nm is thus lost. This new technique is compared with a commercially available instrument, and sensitivity limitations are discussed.
ABSTRACT
We demonstrate that picosecond mode-locked laser-based degenerate four-wave mixing can be detected with good signal-to-noise ratios in an optically thin flame and that detailed turbulence statistics can be acquired by use of this technique. A regeneratively mode-locked Ti:sapphire laser was tuned to the 4(2)S((1/2))-4(2)P degrees ((1/2)) transition in atomic potassium (which was doped into the flame) at 769.9 nm. Using the all-forward degenerate four-wave mixing geometry, we achieved signal-to-noise ratios of 70:1 without the use of a spatial filter. A sensitivity curve and a method for acquiring turbulence statistics are presented.
ABSTRACT
The initial work on the use of acoustic signals to feedback control the length of an optical substrate to the order of 10(-6) parts in 10(6) is described.
ABSTRACT
This control system randomly scans a Q-switched diodepumped Nd:YLF laser from hertz to kilohertz repetition rates with less than +/-5% (3sigma) pulse-energy jitter.
