Single-Mode Fiber Laser Marking
May 16, 2013-
Figure 2 in the sequence shows examples of the capabilities of single-mode fiber lasers, for marking samples in stainless steel, ceramic, and Datamatrix™. From left to right: 100-micron (0.004-in.) high text marked in stainless steel; text marked on a 0.18X0.15-in. ceramic chip; and a 0.02-in. square 18X18 Datamatrix™ code in copper foil.
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Figure 3 shows examples of the capabilities of single-mode fiber lasers, for marking samples in epoxy, stainless steel, and brass tubing. From left to right: 0.014X0.03-in. 2D code in epoxy; banding on 0.06-in. diameter 304 stainless steel; and text in 0.06-in. diameter brass tubing.
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Figure 4 compares the speed of single-mode versus multi-mode lasers. On the left, the effects of a single-mode fiber laser at 117 ms; on the right, those of a multi-mode fiber laser at 266 ms. The mark on the left, made in steel with a single-mode laser, took less than half the time to complete as the mark on the right, which used a multi-mode (higher order) laser using the same optical setup.
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In Figure 5, we see that single-mode fiber lasers achieve finer resolution and increased field size than standard fiber-laser markers, and can provide the same mark resolution while using a longer focal length optic.
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Figure 6 shows the effects of single-mode fiber lasers for micro machining are seen in several examples. The photo on the left shows the result of using a single-mode fiber laser to drill a 0.008-inch diameter micron hole, ±0.0005-inch tolerance in 0.008-inch thick steel, with no post processing. The center shows a 0.02-inch diameter drilled into 0.03-inch thick alumina with no micro cracking. The right shows a 0.001-inch wide channel cut into a medical tube.
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Figure 7 is a comparison of depth and hole size in steel resulting from a 50-W single-mode fiber laser (left) and regular 50-W fiber laser (right, for the same processing time. The single-mode laser drills deeper in the same amount of time, with a small entry diameter.
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In Figure 8, cut resolution and level of thermal heat input control are illustrated. On the left, a 0.004-in. thick stainless steel part is cut from a lead frame. On the right is a 0.015-in. copper inlay cut out, showing a close up of the cut resolution and level of thermal heat input control.
There are two types of fiber lasers, single mode and multi mode. Single-mode fiber lasers typically are delivered via fiber with a core diameter of less than 25 microns, producing a narrow, high-intensity beam that can be focused down to a spot size as small as 20 microns. This high-intensity, small spot is ideally suited for fine laser marking, micro machining, or cutting applications.
Multi-mode (also called higher order mode) fiber lasers, by contrast, use fibers with core diameters greater than 25 microns, resulting in lower-intensity beam and larger focused spot sizes.