With lasers that operate in the nanosecond range, the marking process is always accompanied by significant heating of the target material due to the laser energy it absorbs, which makes it difficult or even impossible to mark easily damaged or highly sensitive materials without compromising their texture. With pulse widths in the picosecond range, however, enormous pulse powers can be achieved in conjunction with low heat input. The pulse width is short enough that heat is not conducted sufficiently quickly to significantly heat the surface. Ideally, the area of the material on which the laser beam is acting will transition directly from the solid phase to the gas phase, drastically reducing the occurrence of burring. The extremely limited impact of heat is probably the ultrashort pulsed laser’s greatest advantage. This “cold laser marking” process opens up a whole host of applications that would not otherwise have been feasible, such as marking easily damaged and highly sensitive materials used in medical applications, sensors and the aerospace industry. The shorter pulses cause less damage to the surrounding material and afford greater precision in terms of material removal, allowing for incredibly fine marking. The benefits range from improved surface quality to a greater level of detail and a more exact result.
Amongst its many applications, ACI’s DFL Brevis Marker is particularly well suited to burr-free engraving of stainless steel, hardened steel, aluminium or glass. Additionally, identifiers can be marked in black on raw aluminium, stainless steel and high-speed steel in next to no time and without the need for surface finishing beforehand. USP lasers can also be used to achieve colour changes on plastic, to mark silicones and to cut thin materials.