Laser processing simply means performing a specific task using lasers. Usually,this involves processes like cutting, drilling or puncturing, engraving, and welding. Apart from being more precise compared to using tools such as power saws and drills, laser processing can work with a variety of materials – from the very delicate to the very durable – with ease and accuracy.
However, much like other tools, there are elements to laser processing that should be taken into consideration so that it can perform its job properly and safely. One such element is focusing.
Light Beams and Focusing
Have you ever played with a magnifying glass as a child? If so, then you’ve probably tried to use it to set a piece of paper on fire, which most likely took quite a long time. That’s because your arm can’t maintain the right position long enough to concentrate the sunlight onto one single spot and heat it up enough to burn the paper. If you stray even just a millimeter from that position, the light will go dull and you’d have to find the right position again to focus the beam of sunlight, starting the process all over.
This childhood experiment explains the most basic concept of focusing, and how important it is for laser processing. Only by maintaining a specific angle to focus the beam of light onto a specific position will the laser be able to do its job properly.
How Focusing Affects Laser Processing
Of course, laser processing isn’t simply about pointing and holding the laser beam onto just one spot (called the burn area or burn pattern) so that it doesn’t stray from its intended path. For example, lasers with higher intensities are needed for cutting or marking extremely tough materials like titanium. High-grade lenses help focus the laser onto the surface of the material to give it the cutting power it needs to cut or engrave the material. Meanwhile, high-quality linear stages ensures that even the smallest deviations in the patterns are followed.
Other factors to be considered included the thickness of the material; the thicker the material, the wider burn area is required and vice versa. By controlling how near or far the laser focusing lens is to the material, the operator can control how wide or narrow the burn area would be. The correct burn area is necessary so that the molten material can be quickly cleared from the cut or hole made by the laser, resulting in precise, clean outputs. The actual material being used also affects the focusing requirements of the laser. Cutting carbon steel requires a smaller burn area, for example, whereas stainless steel or aluminum requires a wider burn area for the laser to be effective.
Focusing also helps the laser accomplish its job faster and more efficiently. The wrong focus will still be able to accomplish the task, but it would also use up more resources which is not an ideal scenario. What’s more, the output will probably be of lower quality. The edges may be rougher or uneven, for instance, or the welds may be too big and unwieldy for a delicate product (say, a medical implant). Maintaining the right focus intensity and position ensures the repeatability of the parameters, as well as producing consistent high-quality edges and surfaces. Finally, changing the focus of the laser allows quickly switching from high-pressure to low-pressure, as needed, in processes like cutting or drilling.
Lasers are already an amazing technology by themselves. However, with the use of other technologies such as positioning and focusing, not only do they get the job done but they get it done in half the time and half the cost.