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fiber laser advances
remote laser processing
HIGH-INTENSITY BEAM CUTS AND WELDS
HIGH-HEAT CONDUCTIVE METALS
LYNN SHEEHAN, DAHV A. V. KLINER,
and MICHAEL ATCHLEY
The introduction of the high-power fiber laser with brilliant beam qual- ity has enabled rapid development of remote laser scanning (RLS) applica- tions. In comparison with other tech- nologies, RLS offers increased flexi- bility, higher operational speed, and
reduced cycle time to process a wide range of workpieces.
We will describe how high-brightness (beam parameter
product [BPP] < 1. 5 mm-mrad) fiber lasers can achieve key
performance benefits for remote laser processing. Because of
their optical characteristics, high-brightness sources allow the
system integrator to leverage larger standoff distances from the
workpiece, providing a safer operating state for the optics. With
the ability to achieve high intensity (small spot size) and fast
beam positioning, we have demonstrated cutting, ablation, and
welding of high-heat conductive metals such as aluminum and
copper, as well as of new lightweight carbon fiber composites.
High-brightness fiber laser
The nLIGHT alta next-generation fiber lasers employ a novel
architecture [ 1] that houses the pump diodes and drivers in
standalone pump modules and the gain fibers in a configu-
rable gain module that can generate >4k W of output power.
The gain module is based on a novel master-oscillator/pow-
er-amplifier (MOPA) design that enables a high-brightness
output (FIGURE 1). This design differs from legacy fiber lasers,
which employ fiber combiner technology to add the outputs
of many lasers and thus deliver an inherently lower brightness.
This laser also incorporates a robust, integrated back-reflection
isolator that protects all of the modules from back-reflections
generated by the workpiece, enabling stable, uninterrupted
processing of highly reflective materials. We will show how
these two advances benefit RLS applications.
Key aspects of RLS for system design are the scanner standoff distance, spot size at the part, and scan field. One benefit
of using high-brightness fiber lasers is their ability to increase
standoff distance and scan field, while simultaneously providing a small spot size for higher weld speeds and deeper weld
penetration. The TABLE contains an example of two commercially available RLS scanner products (SCANLAB Intelli WELD
and IntelliSCAN) that show the benefits of higher brightness
(represented by 50µm fiber core size). From this example,
one can see that the user can benefit from a more than 50%
FIGURE 1. The nLIGHT alta next-generation fiber laser (a) and
examples of its high-brightness performance (b).