CuBr laser in measurements of fluid-flow fields with PIV method

Abstract

Pulsed metal vapour lasers in general, and pulsed copper vapour lasers in particular are now considered to be enabling technology for a number of important processes. The pulsed conventional copper vapour lasers (CVLs), the technology of which has continued to develop to the point today where multiple green/yellow laser beams of more than 1 kilowatt average power are routinely generated at around 1% efficiency (Lawrence Livermore National Laboratory), are the highest power visible lasers ever developed. Today the conventional CVLs producing 100 W average power at 5 kHz pulse recurrence frequency and about 1% efficiency are at the laser market. However, due to their high operating temperatures (1500-1600 degree(s)C), the conventional CVLs are of complex construction, require flowing gas system, and have long warm-up time (90-120 minutes). The pulsed copper bromide (CuBr) laser is another representative of the copper laser family, which does not exhibit the disadvantages associated with the conventional devices. CuBr lasers have been demonstrated to have high-efficiency (2-3%) and high specific output powers (0.1-1 Wcm<SUP>-3</SUP>). Up to now a CuBr laser of 120 W average output power has been reported. There is no other type of laser which can deliver such a high average power in the visible range with such a high efficiency and high beam quality. The rapid development of laser technique in the past decade allows to introduce new methods of measurements into various areas of scientific and technical activities. One of the possibility is to apply the laser technique to visualisation of flows and to particle image velocimetry (PIV). In this paper we present the potential of CuBr laser in this field.