Hilbert transform method for analysis of ESPI for the studies of dynamic events

摘要

In this paper we proposed a Hilbert Transform to calculate the phase map. The data processing is performed in temporal domain, considering the temporal history of the interference signal at every single pixel. This results in a relatively high spatial resolution of the phase map. In addition, the phase method enables a fully automatic and does not require human interaction. The final results give a temporal development of two-dimensional deformation field. To reduce the influence of the fluctuations of bias intensity on the calculated phase, it was removed prior to performing the Hilbert Transform. The proposed method for analysis of the phase of dynamic ESPI was examined in two different experiments, i.e., plastic deformation studies, and thermal expansion studies. The dynamic range of measurements is increased from several tens of nanometers to several micrometers, which makes the method very attractive for dynamic measurement.