A data-driven approach for determining time of initial movement in shock experiments using photonic Doppler velocimetry

Photonic Doppler Velocimetry is an interferometric technique for measuring the beat frequency of a moving surface, from which the calculated velocity profile of the surface can be used to describe the physical changes the material undergoes after high-impact shock. Such a technique may also be used to characterize the performance of small detonators and determine the time at which the surface began moving. In this work, we develop a semi-automated technique for extracting the time of initial movement from a normalized lineout of the power spectrogram near the offset frequency of each probe. We characterize the response bias of this method and compare with the time of initial movement obtained by hand calculation of the raw voltage data. Results are shown on data from shock experiments such as gas gun setups and explosives-driven flyer plates.