Determination of the laser beam quality factor (M²) by stitching quadriwave lateral shearing interferograms with...

A complete complex amplitude reconstruction method for the determination of the laser beam quality factor M² 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 M² factor is provided. The experimental results demonstrate that the new method can be an accurate means to measure the M² factor. The proposed method can avoid the influence of phase inaccuracy in the small signal area of the interferogram, during the measurement of the M² factor.