Silicon micromirrors can guide laser beams at extremely high speeds, allowing operators to dose heat input to workpieces with absolute precision. But to date, they have not been robust enough to be used for laser cutting and welding. Researchers have developed fast, durable mirrors that are capable of performing challenging cutting and welding tasks.

Fast, resilient MEMS mirrors deflect the laser beam and guide it precisely over the workpiece, enabling them to process aluminum and sheet steel. (© Fraunhofer ISIT)

New laser MEMS mirrors etched from silicon are at the heart of the flexible laser system. These MEMS mirrors are scanning mirrors that deflect the laser beam and guide it precisely over the workpiece. Up to now, it has been possible to use these small mirrors only with laser outputs of a few milliwatts. This was enough for head-up displays on car windshields, but not for laser cutting and welding. Higher outputs would have melted the mirrors.

Thanks to a new protective coating and a special mounting, the mirrors are now able to withstand even laser powers in the kilowatt range – enough to process aluminum or sheet steel. Copper and aluminum can be welded together using heat input to precisely control which metal heats up more, and thus makes up more of the melt.