Measurement of M2-curve for asymmetric beams by self-referencing interferometer wavefront sensor

Abstract

For asymmetric laser beams, the values of beam quality factor M2x and M2y are inconsistent if one selects a different coordinate system or measures beam quality with different experimental conditionals, evenwhen analyzing the same beam. To overcome this non-uniqueness, a newbeamquality characterization method named as M2-curve is developed. The M2-curve not only contains the beam quality factor M2x and M2y in the x-direction and y-direction, respectively; but also introduces a curve of M2xα versus rotation angle a of coordinate axis. Moreover, we also present a real-time measurement method to demonstrate beam propagation factor M2-curve with a modified self-referencing Mach-Zehnder interferometer based-wavefront sensor (henceforth SRI-WFS). The feasibility of the proposed method is demonstrated with the theoretical analysis and experiment in multimode beams. The experimental results showed that the proposed measurement method is simple, fast, and a single-shot measurement procedure without movable parts.