Time-lens Photon Doppler Velocimetry (TL-PDV) for High Velocity Dynamic Range Experiments

High energy density experiments such as inertial confinement fusion (ICF) produce extreme velocities that can exceed 100 km/s. However, the velocity dynamic range for photon Doppler velocimetry (PDV) systems is limited by the bandwidth of the recording electronics to typically < 20 km/s. Techniques in the literature such as leap-frog PDV and time-stretch PDV address this issue by either introducing a large beat frequency offset using local oscillators with different wavelengths, or by optically expanding the temporal signals using dispersion, respectively However, these existing approaches present numerous tradeoffs in terms of complexity and performance. Here we experimentally demonstrate a novel PDV approach termed time-lens PDV (TL-PDV) that addresses these tradeoffs. Compared to existing approaches TL-PDV offers reduced hardware complexity, is more efficient in optical bandwidth usage, requires minimal changes to the existing PDV set-ups, and maintains large record length. Experimentally, we demonstrate a TL-PDV system that can achieve a 74 km/s velocity dynamic range using only 12.5 GHz of electrical bandwidth. Furthermore, we measure equivalent velocity uncertainties < 100 m/s and demonstrate real-world operation on laser driven flyer experiments in the range of 1 km/s.