Simultaneous multiple time scale imaging for kHz-MHz high-speed accelerometry

Fast transient events,such as the disintegration of liquid bodies or chemical reactions between radical species,involve various processes that may occur at different time scales.Currently,there are two alternatives for monitoring such events:burst-or high-speed imaging.Burst imaging at ultrahigh speeds(~100 MHz to THz)allows for the capture of nature's fastest processes but only for a narrowly confined period of time and at a repetition rate of~10 Hz.Monitoring long lasting,rapidly evolving transient events requires a significantly higher repetition rate,which is met by existing~kHz to 1 MHz high-speed imaging technology.However,the use of such systems eliminates the possibility to observe dynamics occurring on the sub-microsecond time scale.In this paper,we present a solution to this technological gap by combining multiplexed imaging with high-speed sensor technology,resulting in temporally resolved,high-spatial-resolution image series at two simultaneous time scales.We further demonstrate how the collection of such data opens up the tracking of rapidly evolving structures up to MHz burst rates over long durations,allowing,for the first time,to our knowledge,the extraction of acceleration fields acting upon the liquid bodies of an atomizing spray in two dimensions at k Hz frame rates.