This paper investigates the effect of partial speckle decorrelation due to the transverse component of the object displacement on the phase measurement using statistical optical theory. The theoretical values of statistical phase errors are derived under the in-plane and out-of-plane displacement sensitive arrangement when using the phase subtracting method. The selection of the optimum system parameters is also discussed. The theoretical and experimental results show that this phase extracting method is sensitive to speckled and additive noise.
"Statistical analysis of phase-stepping digital speckle-pattern interferometry", Proc. SPIE 1755, Interferometry: Techniques and Analysis, (5 February 1993); doi: 10.1117/12.140779; https://doi.org/10.1117/12.140779