Shock wave characterization using a multi-exposed high-speed camera and high performance fiber optics sensor.*

We will present planar shock wave imaging to determine velocity and pressure that is based on multi exposure of each frame in the high-speed imaging series. The technique is demonstrated using a custom-built illumination source where the illumination pulses are much shorter than the frame exposure time of each frame. The benefit of the presented method is speckle free imaging with the sub nanosecond illumination pulses and a minimal spacing between the pulses of few nanoseconds that can be arbitrary delayed in respect to the event under the investigation. This enables capturing the shock waves right after the emission at multiple time instances. The presented method surpasses previously demonstrated multi-exposure methods by an order of magnitude in time resolution, is suitable for transient events, and is not limited to a homogenous shock wave emission, i.e. extends streak imaging-based techniques. The technique gives detailed insight into the shock wave pressure evolution near its source with the measured shockwave pressure amplitudes reaching 1 GPa. The results from a multi-frame multi-exposure shockwave pressure/velocity measurement technique are verified with a custom-made high-bandwidth high performance fiber optics sensor.