ABSTRACT
Laser marking often takes the form of an alphanumeric code imprinted on the label or on the surface of the product to describe date of manufacture, best-before, serial number or part number, but the mark can also be a machine-readable barcode or 2D symbol. The imaged-mask marking technique described earlier for pulsed CO2 laser marking is also used for excimer marking although, due to the markedly different wavelength, optical components such as lenses and mirrors are made from different materials. Although ink marking may provide a higher-speed process and a bolder mark, the main advantages of laser marking in this market are indelibility and reliability. The key to cosmetically attractive laser marking is to have the laser light absorbed within less than 0.1 mm of the surface of the material to be marked. An equally important aspect of decorative laser marking is the response of the polymer being marked to the deposited laser energy.
