Using BeamWatch AM, we can see in the left graph a diffraction influencing the laser beam; on the right, there is a clear Gaussian profile. The focus shift and the different direction of the beam from X- to Y-axis result in reduced power density within the larger focal point. This explains the deterioration of the surface and loss of material strength.
The detailed measurement provided by BeamWatch AM allowed the engineers to quickly find the reason for the quality issues: The beam path had been misaligned between collimator and the focus shifter, clipping one side and causing the asymmetric beam profile and propagation difference between X- and Y-axis. Once the optical elements were been adjusted, the power density grew with the smaller focus. The quality issues were resolved without external support by the manufacturer of the machine.
When asking the SLM manufacturers and users about what they need to know about the laser beam, the first answer we mostly get is, the cross section of the beam profile. The example above shows clearly that this is not the clue to most problems. BeamWatch AM delivers significantly more information and can track changes over time at video rates. The system allows for the delivery of completely new beam measurements, such as astigmatism or real time focus shift.
Extensive testing made with the Rayleigh scatter technology also shows that BeamWatch achieves ISO-compliant measurements. It has been demonstrated that the methods used to obtain and refine the BeamWatch data validate the claim that the technology meets ISO 11146 standards. Adding to that the simplicity of setup, results in a new, valuable service tool for SLM system manufacturers or trained users.