| Abstract Scope |
In the past decade, handheld laser beam welding (HLBW) devices have steadily emerged, along with their applications, particularly for thin plate welding. However, in handheld procedures, the spot size and power density are constantly subject to variations, as they depend on the welder’s experience and the ability to maintain a steady torch position and travel angle. In this context, accurate characterization of the laser beam profile becomes essential to achieve optimal results not only in welding, but also in other applications. This work focused on developing a method to profile the caustic of a fiber handheld laser beam welding machine and evaluate how its geometry is affected by changes in the travel angle and torch extension. To acchieve this, the beam analysis devices Primes® FocusMonitor FM+ and PowerMonitor PM48 were used to measure the caustic of a Miller OptXTM 2 kW HLBW machine. Profiling routines were carried out over a length of 50 mm (Z0 ± 25 mm) at laser beam powers of 210, 400, 600, 800 and 1000 W. The profiled beam exhibited a narrow waist, with average spot diameter of 50 μm at Z0, a Rayleight length of 1.25 mm, and a divergence angle of 40.6 mrad. The Beam Parameter Product (BBP) and propagation factor (M2) were, in average, 0.48 mm.mrad and 1.4 respectively. The power efficiency showed a slight decrease with increasing power, and the focus shift was approximately 0.6 mm. The proposed methodology proved accurate and reliable for HLBW applications. The results confirmed that beam geometry is highly sensitive to torch positioning, reinforcing the importance of precise handling in handheld laser welding operations. |