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Laser cutting is a way to cut precise patterns in metal, plastic, wood, and practically every other material that man works with. It allows a level of accuracy and complexity impossible with conventional machining tools. Laser cutting works by exciting a gaseous medium, commonly carbon dioxide, causing it to amplify light reflected back and forth multiple times within the laser chamber. The light emerges from an aperture and is focused by a lens onto a specific point.
A typical process laser has a beam about a 1/5 of a millimeter in width, focusing 1000 to 2000 watts of energy. This is enough to melt most common materials. Because lasers become less focused and lose energy as they penetrate through a material, there is a limit of about 20 mm for the deepness of the cut. Laser cutting machines are integrated into a larger CAD/CAM (computer-aided-design, computer-aided-manufacturing) system that takes a design file and implements it on a workpiece. These machines represent a stepping stone in the continuing trend away from hands-on manufacturing, putting human workers in a more removed, creative design role.
Because a laser is made up of photons, parts of its energy can be reflected away by materials such as aluminum and copper alloys. These materials are also thermal conductors, meaning they distribute incoming heat more evenly throughout their volume. For this reason, carbon alloy and stainless steel are popular workpiece materials for laser cutting. They are poor at absorbing heat, so heat is concentrated into the laser's path more readily.
Typical laser cutters allow features as small as 1 mm in size. Specialized lasers often feature sizes that are even smaller, allowing the fabrication of true micromachinery. The first laser cuts were made in 1967, as part of a spin off of a military research project focused on lasers. Because the beams used in cutting are "class 4" lasers, the machines are designed to ensure that human operators are never exposed to them directly. All the cutting is done inside the machine.