High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser

Flow and thermal characteristics of high Reynolds number (2800-17,000) dye cell: simulation and experiment

This paper presents computational and experimental studies on wavelength/frequency fluctuation characteristics of a high pulse repetition rate (18 kHz) dye laser pumped by a frequency-doubled Nd:YAG laser (532 nm). The temperature gradient in the dye solution is found to be responsible for wavelength fluctuations of the dye laser at low flow rates (2800<Re(d)<5600). The turbulence Reynolds number (ReT) and the range of eddy sizes present in the turbulent flow are found to be responsible for the fluctuations at high flow rates (8400<Re(d)<17,000). A new dimensionless parameter, dimensionless eddy size (l(+)), has been defined to correlate the range of eddy sizes with the experimentally observed wavelength fluctuations. It was found that fluctuations can be controlled by keeping ReT≈10 and lmax(+)≈1. The simulated result explains the experimental observation and provides a basis for optimizing the dye solution flow rate for high PRR pumping.

Experimental techniques for imaging and measuring transient vapor nanobubbles

Imaging and measuring transient vapor bubbles at nanoscale pose certain experimental challenges due to their reduced dimensions and lifetimes, especially in a single event experiment. Here, we analyze three techniques that employ optical scattering and acoustic detection in identifying and quantifying individual photothermally induced vapor nanobubbles (NBs) at a wide range of excitation energies. In optically transparent media, the best quantitative detection can be achieved by measuring the duration of the optical scattering time-response, while in an opaque media, the amplitude of the acoustic time-response well describes NBs in the absence of stress waves.