Extended-range temporal electronic speckle pattern interferometry

Abstract

In recent years the availability of high-speed digital video cameras has motivated the study of electronic speckle pattern interferometry ͑ESPI͒ in the time domain. To this end a properly sampled temporal sequence of N-fringe patterns is used to analyze the temporal experiment. Samples of temporal speckle images must fulfill the Nyquist criteria over the time axis. When the transient phenomena under study are too fast, the required sampling frequency over time may not be fulfilled. In that case one needs to extend the measuring range of the algorithm used to extract the modulating phase. We analyze how to use short laser pulses or short video acquisition times with fairly long temporal separation among them to estimate the modulating phase of a dynamic ESPI experiment. The only requirement is that the modulating phase being estimated be properly sampled in the spatial domain.

High-speed electronic speckle pattern interferometry for analysis of thermo-mechanical behavior of electronic components

“…Another common problem is the speckle decorrelation under large out-of-plane deformations [17]. A typical deformation range of electronic components at working temperatures is of the order of several micrometers.…”

Sampling Rate in the Dynamic Speckle Analysis

“…Knowing the effect of sampling rate over an index value, a researcher will be able to establish criteria to choose the appropriate sampling rate for a speci c monitored phenomenon [10], [11], [12].…”