Beam Profiling of 1 KW Fiber Laser with Camera-Based Profiling System

Laser System
Fiber laser source

  • 1070nm
  • 600μm fiber
  • CW
  • 1 KW max average power

5-axis movement
Class 1 workstation
125mm focusing lens

Fiber Laser
Figure 1. Profiling setup
Spiricon Beam Profiler
BeamGage Professional
SP620U camera
LBS-300-NIR with SPZ17015 beam
splitter on input
  • ND 1.0 + 0.7 used for 350W to 750W

13.5% of peak bam diameter measured method applied

Results
Setup and location of the beam was relatively simple. The X and Y movements were used in conjunction with the 633nm target laser to center the beam on the camera chip. Once the beam was located and an approximate Z position was made using the target laser, the motorized Z stage was used to tweak in the image of the focused spot.

We took profiles at 350W, 500W and 750W. We could have taken a profile at 1000W, but the tooling plate we were using for the beam dump was taking a beating and they didn’t want to push it higher than that. The images resulted in an elevated background, but it was not due to a lack of UltraCal. We were using a piece of steel tooling for a beam dump and I suspect that the amount of scattered light from the tooling was enough to elevate the background. Manual draw shape was used for beam diameter measurements. Customer will purchase a beam dump.

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

Customer was expecting a Gaussian profile, but more of a flat top profile was what resulted.

Between the demonstration and the system sale, the customer added the requirement to be able to check focused spot +/- 12mm. This could only be achieved by adding a -100mm lens and BeamGage will apply an optical scale to compensate for the resulting larger beam diameter.

See picture of beam profiling images on following page…

Pictures of Beam Profiling Images
 

Fiber Laser Fiber Laser
Figure 2. Profile at 350W (no Z-scale adjustment) Figure 3. Profile at 350W (with Z-scale adjustment)
Fiber Laser Fiber Laser
Figure 4. Profile at 500W (no Z-scale adjustment) Figure 5. Profile at 500W (with Z-scale adjustment)
Fiber Laser Fiber Laser
Figure 6. Profile at 500W (no Z-scale adjustment) Figure 7. Profile at 500W (with Z-scale adjustment)

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