Abstract: Surfaces of silicon wafers used in making computer chips are marked by dimples engraved by pulses of radiation from a Nd:YAG or Nd:YLF laser pumped by diode lasers (commonly called a DPY laser). A beam of radiation from the DPY laser is focused on and moved across the surface of a wafer so as to produce dimples in a cluster positioned on a microgrid subdividing elements of a dot-matrix representation of a text written in alpha-numeric or bar-code characters.