Determination of the laser beam quality factor (M) by stitching quadriwave lateral shearing interferograms with different exposures.

A complete complex amplitude reconstruction method for the determination of the laser beam quality factor M based on the multiple exposure of a quadriwave lateral shearing interferometer (QWLSI) is presented. The theoretical analysis and simulation of the influence of the information in the small signal area on the calculation of the M factor is provided. The experimental results demonstrate that the new method can be an accurate means to measure the M factor.