A laser at 355 nm, made by converting infrared light to ultraviolet in a crystal (frequency tripling). The short wavelength is absorbed very strongly, so it does “cold marking” without heat stress.

A gas laser (10,600 nm) that uses a CO₂, nitrogen and helium mixture in a sealed tube. Its long wavelength is absorbed well by organic materials.

An infrared laser (1090 nm) that generates its beam by pumping light through rare-earth-doped glass fibres. It is built mainly for metal marking.