Polyesters are a class of polymers that include PET (polyethylene terephthalate), PET-G and Mylar^®. Laser processing of polyesters can be performed with either a 9.3 or 10.6 micron CO₂ laser. Polyesters do not readily absorb the energy from the 1.06 micron fiber laser and is not recommended for this material. Laser cutting of polyesters with a CO₂ laser results in clean edges free of discoloration and limited melting. Laser engraving of polyesters with a CO₂ laser results in depth, high contrast, and limited melt back at the point of ablation. Laser marking of polyesters with a CO₂ is not recommend as the wavelength will not make a contrasting mark.