Real-time monitoring of beam quality according to ISO 11146

The revised optical design ensures that the diffraction index – M² – can be determined for even a single laser pulse.

This applies to femtosecond lasers, as well as to pulses in the millisecond range, and cw lasers. Since the system does not have any moving parts, the measurements can be reproduced at any time and thus always comply with ISO 11146 specifications.

The BWA-MON performs all measurements simultaneously, providing a very good signal-to-noise ratio. This applies to the values of the first Rayleigh length required by the ISO standard, as well as to those outside the second Rayleigh length.

The beam parameter product (M²×λ/p) indicates how well a laser beam can be focused. Real-time monitoring allows deviations to be detected and corrected at an early stage. This is particularly important in high-precision application areas such as additive manufacturing and laser material processing, in which even small deviations in the focal point have a serious impact on the functionality of the overall system.

Focus shifts are usually caused by so-called thermal lenses, which occur when a laser beam hits an optic and heats it up. This typically takes less than 30 seconds. Conventional beam analysis methods cannot perform ISO-compliant measurements in such a short amount of time. Therefore, it has not been possible until now to capture the dynamics of the formation of a thermal lens.

“The BWA-MON has made it possible for the first time to dynamically track how the focus shifts through thermal lenses,” says René Sattler, Product Engineer at LASER COMPONENTS Germany. “The latest adjustments have once again significantly improved the system’s signal-to-noise ratio. In addition, there is a new user-friendly software available. In Europe, we will present the latest optimised version of this M² measuring device for the first time at LASER World of Photonics.”