Stress Perturbations Caused by Longitudinal Stress Gauges
In general, the diagnostics used to evaluate the shock state parameters in samples loaded by stress waves perturb the fields they are measuring. For example the insulating layers in which stress gauges have to be mounted in a conducting sample usually result in impedance mismatched interfaces. Similarly, velocity interferometry inevitable requires the wave to interact with a mismatch interface. In such situations wavelets generated by the parts of the wave that arrive early at the mismatch interface reflect back into the sample and interfere with the later-arriving parts of the wave.