Characterizing a Laser Used in Metal Additive Manufacturing Equipment

A developer of power-bed additive manufacturing systems needed a beam profiling system that could be used by their field technicians for setup and maintenance of customers’ lasers. The view of the caustic was not as important as the laser measurement results. The cumbersome water-cooled system they had been using was costly, and lead times for sale and repair were long. Moving to a BeamGage® based system made setup quick and finding the focal spot location easy

Author:

John McCauley, Midwest Region Sales Manager, Ophir-Spiricon, LLC

Laser Information

  • Make: IPG
  • Laser Application: Laser Additive Manufacturing
  • Source: Fiber
  • Wavelength: 1070 nm
  • Rated Power/Energy: 400 W
  • Expected Beam / Spot Size: 70-100 μm

Laser Measurement Products

  • Beam Profiling Imager: SP300 High-Resolution Camera
  • Beam Profiling Software: BeamGage® Professional
  • Power / Energy Measurement: None
  • Additional Equipment: LBS-300-NIR

Their routine is to take a series of beam profiles to compile an exploded view of the caustic with 2D profiles. They place the profiler where they expect the focus to be, raise the profiler 13mm, and take 27 beam profiles in 1mm increments until the entire caustic has been imaged at +/-13mm from focus.

The two results that are most important to them are:

The "d0" measurement, which is the diameter of the beam at the z0 location, The "z0" measurement, which is how far off of the expected location of the focused spot relative to the beam profiler and how it was set up, and The "zR" measurement, which is a measurement of the Rayleigh length.

They want M2 and/or BPP measurements, but these are not as critical to their setup.

Twenty seven (27) beam profiles were then collected at 1mm increments through focus at the 10% (~40W) and 25% (~100W) levels. A single data file was collected at the two different power levels.

Demo Setup

Measurement Results

1/e2 beam diameter calculation method used

Measured Beam / Spot Size: ~70μm

Results: At 10% (~40 W) / -13 mm, -6 mm, and 13 mm.

-13 mm
-6 mm
13 mm

Results: At 25% (~100 W) / -13 mm, -6 mm, 0 mm, 6 mm, and 13 mm.

-13 mm
-6 mm
0 mm
+6 mm
+13 mm
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