Nowadays, people use fiber laser engravers to make permanent marks on metal. When you are engraving, a focused beam of light is sent through a fiber optic cable and used to mark the surface of the material. The surface absorbs the laser, melts, and discolors.
All lasers have three main components — an energy source, a laser medium, and an optical resonator. The energy source is where a laser gets its energy. Many different laser media can be used as the base of a laser. The optical resonator, or optical cavity, reflects the light, so it feeds back into the system.
Materials are exposed under laser marking machines to a low-powered beam. This doesn't affect the properties of the materials, but instead uses a process called laser coloration on the surface to create high-contrast markings.
The laser beam created with a galvano metric drive system moves in one or two dimensions. With a traditional lens, the focal point of the beam changes as the beam moves away from the optical axis. This change in focal point can result in defects in your projects. F-theta lenses correct this problem by focusing the laser beam onto an image plane without distortion.
theta lenses are often used in galvanometric scanning systems that are comprised of two mirrors. One mirror controls beam deflection in one direction and the other controls beam direction in the perpendicular direction. The F-theta lens then focuses the laser precisely on the planar surface.
Materials you can engrave or mark with fiber lasers include: Acrylic, Hard plastics, Brick, Granite, Marble, Tile, Aluminum, Gold, Silver, Stainless Steel, Brass, Titanium, Tungsten and so on.
Fiber lasers work well on PVC (polyvinyl chloride) materials. However, some PVC acrylics can create toxic fumes when they're lasered. PVC is a polymer that contains chloride. Heating PVC breaks it down, causing it to release hydrochloric acid, a toxic gas. If you're using a fiber laser on PVC, you'll need to make sure you're using a trustworthy fume extraction system capable of handling the toxic gas.
Another consideration when using PVC with a fiber optic laser is dechlorination, a decomposition process that occurs as PVC is heated. When the chlorine is released, it causes yellowing around the area that was marked with the fiber laser.