Evolution of a real-time laser M2 measurement system

In 2011, the authors introduced a multispot, real-time M2 measurement technology that fulfilled the missing ability of the existing M2 measurement systems to dynamically measure thermal lensing in high-power fiber laser systems. Over the next years, the technology has evolved making the technology of M2 measurement compact, easier to use, and more accurate. The traditional M2 measurement technology, being a time-averaged measurement, is incapable of seeing transient changes in a laser system’s M2, let alone thermal lensing. The multispot approach provides an M2 measurement in a single laser pulse or at the frame rate of the pixelated sensor being used. This paper covers the evolution of the multispot M2 measurement technology and how it has matured into a state-of-the-art M2 measurement tool.