Laser beam diagnostics for pulsed Nd:YAG lasers

Abstract

The increased use of lasers for cutting, drilling and welding in industrial applications has accentuated the need for effective laser beam diagnostics techniques. In this paper, the results are presented of a comparative study of the performance of two commercially available laser beam analyzers, a rotating-wire type (LBA) and a rotating hollow-needle type (Prometec Laserscope). Both laser beam analyzers were modified and used to measure the spatial power density distributions and beam “diameters” of converging/diverging laser beams at and about the focal point of a 350 W pulsed Nd:YAG laser welder.While similar in basic concept, there were many differences in functionality noted between these two beam analyzers. The Prometec is easy to use and to understand, but affords no direct access to the measured data. Alternatively, the LBA can be assembled from a few inexpensive electro-optical components, but it is conceptually more complex and its operation is more difficult. It does, however, allow the user direct access to the measured data. In spite of these differences, there was good qualitative agreement between the multimode power density distributions measured using both devices at various positions about the focus of the Nd:YAG laser beam. Also, the measured beam spot sizes and M2 beam quality values were found to be in good agreement.The increased use of lasers for cutting, drilling and welding in industrial applications has accentuated the need for effective laser beam diagnostics techniques. In this paper, the results are presented of a comparative study of the performance of two commercially available laser beam analyzers, a rotating-wire type (LBA) and a rotating hollow-needle type (Prometec Laserscope). Both laser beam analyzers were modified and used to measure the spatial power density distributions and beam “diameters” of converging/diverging laser beams at and about the focal point of a 350 W pulsed Nd:YAG laser welder.While similar in basic concept, there were many differences in functionality noted between these two beam analyzers. The Prometec is easy to use and to understand, but affords no direct access to the measured data. Alternatively, the LBA can be assembled from a few inexpensive electro-optical components, but it is conceptually more complex and its operation is more difficult. It does, however, allow the user di...