WELDING JOURNAL 49 optics, the light goes through a collimator to produce a beam at the optimized diameter to achieve high-quality processing characteristics at the workpiece and to minimize energy densities on the steering mirrors and focusing lens — Fig. 1. In the basic operation of a 2D PFO, after the beam is collimated, it is deflected off a coated optical plate (mirror), which also allows visible light to pass back to an optional camera system. The deflected laser beam then is steered to the workpiece by the combination of two mirrors mounted to precision galvo motors, one for each axis (X axis and Y axis), producing the motion while the part being processed remains stationary. The deflected beam then passes through a series of lenses, called a flat-field lens assembly. This is done because if a single focusing lens was used as you move the beam across the lens, you would pass through different thicknesses of the lens causing different indexes of refraction, and your focal point at the workpiece would shift up and down depending where you were on the lens at the time. By using multiple types of focal lenses in a stack, one can create an area where the laser beam focal plane remains constant. Adding a motorized lens between the input and first galvo mirror one can then create adjustment of During the last few years, remote welding with today’s high brightness fiber delivered lasers has gained global acceptance in the automotive sector. Pictured are both laser welding and cutting shots. Fig. 3 — Productivity of PFO vs. traditional laser fixed optic. Fig. 2 — Examples of PFO 3D equipment.
Welding Journal | January 2013
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