Dynamic measurement of the acoustic streaming time constant utilizing an optical tweezer

The combination of a bulk acoustic wave device and an optical trap allows for studying the buildup time respective forces. In particular, we are interested in it takes to build up radiation force streaming. For that, measure trajectory spherical particle field over time. shape is determined by streaming, both acting on different scales. utilize high temporal resolution ($\mathrm{\ensuremath{\Delta}}t=0.8\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{s}$) trapping setup. With our experimental parameters streaming theoretically have characteristic times $1.4\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{s}$ $1.44\phantom{\rule{4pt}{0ex}}\mathrm{ms}$, respectively. By choosing resonance mode measurement position where induced viscous drag act orthogonal directions, can evolution these effects separately. Our results show that accelerated nearly instantaneously constant velocity, whereas acceleration phase velocity significantly longer. We find average about 17 500 excitation periods ($\ensuremath{\approx}4.4\phantom{\rule{4pt}{0ex}}\mathrm{ms}$) longer develop than one force. This duration four larger so-called momentum diffusion which used estimate buildup. addition, this rather large difference explain why pulsed indeed prevent as has been shown some previous experiments.