Deep Engraving copper electrodes for Electric Discharge Machining (EDM), commonly known as "Spark Eroding" in the Toolmaking industry. For fine detailed jobs that is impossible to machine by CNC machines where you have limitations from cutter diameters.The laser can produce sharp corners.
Typical applications are in plastic die moulds.
The photo shows letters of a height of 2mm engraved 0.5mm deep around the letters. Very high definition was acheived.