Laser System Fiber Source: 1070nm 400 µm Spot / Fiber CW 4 kW Max Average Power Precitech Welding Head 5 Degree Angle 300mm fl Lens X,Y and Z Motion Control Open Class 1 Workstation	Profiling Setup (excluding laser system)
Spiricon Beam Profiler BeamGage Professional SP620U Camera LBS-300-NIR with Beam Splitter on Input ND 2.0 + 0.3 13.5% of Peak Beam Diameter Measurement Method Applied

Results

• Setup and location of the beam was relatively simple. The X and Y movements were used in conjunction with the vision system to center the beam on the camera chip. Once the beam was located and an approximate Z position was made using a relatively low power level, the camera stage was used to tweak in the image of the focused spot.
• Images of the focused spot were made in 400W increments from 1.6 kW to 4.0 kW. Little changes took place in the mode between these power levels, as expected with the high-quality fiber laser - shots of 2 kW and 4 kW are below.
• The SPZ17015 Wedge and the LBS-300 assembly did get fairly warm during the demo, as expected. The damage threshold of this wedge was high enough to withstand the high average powers
• We were able to get close to the focused spot, but perhaps not right at focus. The measurements we were getting were very close to the 400 µm that he was expecting. However the mode, expected to be flat top, was more Gaussian indicating a possible out of focus scenario.
• What we did see was a shift in the focus. We were able to actually watch the spot start out relatively in focus and then slowly go out of focus, the mode becoming less flat and more Gaussian and the spot growing (about 57 µm in diameter between the pictures below), all in a time span of about 3 seconds. You’ll also notice that the spot is moving down at to the right (Centroid moves 14 µm to the right and 11 µm down). This is something that that he was experiencing but had never seen to what degree. Historically, a Primes focus monitor has been what was used to view the focused spot of these lasers, but due to the method at which the beam image is collected, it would never show this shift.

Pictures of Beam Profiling Images

Profile at 2 kW (No Z-Scale Adjustment)	Profile at 2 kW (With Z-Scale Adjustment)
Profile at 4 kW (No Z-Scale Adjustment)	Profile at 4 kW (With Z-Scale Adjustment)
Pictures of Focus Shift
Time: 0 sec Time: 0.75 sec Time 1.5 sec Time 2.25 sec Time 3.0 sec

Read More