Fractional Lau effect with binary gratings: A frequency analysis

A theoretical study of the fractional Lau effect is performed for a Lau set-up equipped with binary gratings. The separations between the two gratings are chosen equal to an elementary distance divided by a positive integer. Fourier components of the observed pattern function are calculated for these distances. Also, this study shows that it is sufficient to study the Lau patterns in a restricted interval of the gratings separation. Experimental and simulation results are consistent with the theoretical predictions. •The explanation of the Lau effect is interesting in itself.•It is a useful tool in the measurement of some physical quantities.•Fractional Lau patterns are very sensitive to the distance between the two gratings.•We have trapezoidal intensities at the observation plane for z = z0/N, provided Nα< 1.