Laser marking is used as a way of permanently marking a physical item for tracking, either for security of quality control reasons. Rather than using a vibrating or rotating tool to engrave a mark on the item, a high-powered laser is used.
While most forms of engraving result in a loss of some of the marked material when it is etched away, laser marking results in essentially no loss of material. Instead, the laser is used to create a shift in the color of the material, creating a visible, virtually indestructible mark with minimal real impact to the item.
Most plastics can be laser marked, and the process is used on everything from identification badges to complimentary pens. Given its indelible nature, laser marking is an ideal choice for bar codes and other forms of inconspicuous tracking.
An added benefit of laser marking is environmental: with no inks or solvents used, the impact is very minimal. As costs lower, this factor becomes a decisive one for many environmentally-conscious companies and individuals.
There are three main results of laser marking, depending on the material affected and the laser used to mark the item. Charring occurs when the absorbed energy heats up the surrounding material enough to create a slight degradation, resulting in a black mark. Foaming occurs in the case of plastic marking when the surrounding temperature is raised enough to cause the polymers to degrade to gasses, forming small bubbles. Ablation occurs when the material becomes extremely hot and the plastic degrades completely, leaving a clean depression.
One particularly popular use of laser marking in recent years has been in the bar-coding and certifying of diamonds. By using extremely tight beams at very low wavelengths well in the deep ultraviolet range, codes can be inscribed in the diamonds with virtually no external damage. A 193nm Excimer laser is used to create a mark so small as to entirely invisible to the naked eye, and non-intrusive enough to make the chances of cracking or chipping close to zero.
Laser marking can be used on all sorts of substrates including wood, metal, and fiberglass. In addition to bar codes and other tracking info, many companies use laser marking to add their logo to parts or products. An added benefit is that the markings can be applied in difficult to reach areas; all that is required is a direct line-of-sight for the laser beam.