Real-time in-focus CO2 and fiber laser beam optimization with a twin hexapod operated beam expander and fully automated beam analysis with simultaneous raw and focused beam measurement

摘要

Laser material processing machines ranging from all kind of applications for different materials face imperfections.Problems such as inhomogeneous raw and focused laser beam diameter and beam mode as well as disturbedcaustic along the working area (especially of a flatbed machine) exist in most machines that use or do not usebeam expanders. Beam expanders are optic assemblies that are used to collimate the naturally divergent laserbeam in order to achieve a more or less parallel propagating beam. Commercially available beam expanderswhich are supposed to play significant role in maintaining close to perfect beam diameter along the working areaquite often do not perform as they are expected, mainly because of misalignment and weak design. Parameterssuch as beam expander distance from laser beam source, dimensions between the optical components of a beamexpander, the tilts and shifts of the beam expander optics should be optimized. A 12m extendible laser testingbench equipped with an in-line raw beam profiler, twin hexapod operated beam expander, in-focus caustic beamprofiler and a beam dump are used to adjust the mentioned parameters and observe the changes on the distortedbeam. A software controlling the motorized bench is used to change the chosen parameters and display the results.The results will yield an optimization of caustic shape through standard calculation of beam parameters. Thisunique equipment enable us to optimize CO_2 or fibre laser beams used for the aforementioned applicationsin relatively short times in comparison to a previously hand operated optic adjustments. Improvements andbenefits achieved such as close to perfect material cuts along the working area of a machine are evaluated usingCLSM/SEM.