Deep Engraving Graphite 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 engraving around the letters at a depth of 0.5mm.
The smallest letters where 0.5mm high x 0.05mm thick! (not visible in photo - TM logo above the "Tuss")