USP-lasers: Increasing Productivity and Optimizing Processes

03/11/2014
Photo: Laser system

Tool system made up of galvanometer and multi-beam scanner, camera and topography sensors; © Pulsar Photonics GmbH

Pulsar Photonics GmbH, a spin-off of the Fraunhofer Institute for Laser Technology ILT, has developed a tool system that significantly boosts the cost effectiveness of using ultrashort pulsed techniques to process materials by turning to a multi-beam approach. Users can employ the integrated measurement sensors to calibrate the tool and establish parameters in advance of material processing as well as to assure quality once the work has been completed.

Over the past few years, the use of ultrashort pulsed lasers in material processing has been riding a wave of success. Reasons include the laser’s outstanding properties as well as the opportunity to process nearly any type of material with the highest degree of precision. Because the range of possible applications is continually expanding, market growth currently stands at between 20 and 25 percent per year. Typically, the technology is used in areas such as mould technology, cutting and drilling for micro components, sieves and filters, as well as thin-film coating for solar technologies and the manufacture of OLEDs. When it comes to micro structuring, however, today’s technology has often found itself pushed to its limits from an efficiency standpoint.

Because of these efficiency concerns, the current tool of choice for large-area surface microstructuring is the nanosecond laser (ns laser) – which has firmly established itself on the market thanks to impressive cost-efficiency. The drawback is that the precision of the microstructuring is limited by the accompanying melt processes; components often require extensive reworking. By contrast, ultrashort pulsed laser produces surface structures that do not require any further processing. They are accurate to within a few micrometers laterally and to within a hundred nanometers in depth.

The dominant role of evaporation in the ablation process with USP lasers means that ablation rates are around a factor of 10 lower than they are with nanosecond lasers. From a business perspective, this has often made using USP lasers to mass produce micro components seem unattractive. What is more, current USP laser systems generally cannot make use of more than 20 percent of the available laser energy in the 50 to 100 watt power range. In an effort to improve the efficiency of USP lasers in this range, researchers from Fraunhofer ILT have developed a technique that allows laser ablation to run in parallel. This multi-beam technology has now been thoroughly tested and enables the laser beam to be split up into more than 100 beamlets. As a result, a workpiece can be processed at 100 places at once, which speeds up the work process accordingly. The technology means that almost all of the capacity offered by current high-performance USP laser systems can be brought to bear on the workpiece.

The researchers have developed a tool system that includes not only intelligent measurement technology but also the option to segment the beam. Beam segmentation essentially boosts the efficiency of workpiece processing itself; the system’s integrated measurement sensors simplify and automate both the definition of parameters during machine preparation and the monitoring of quality once the work has been completed. As a result, the setup process takes far less time than it otherwise might. For instance, users can conduct initial machine preparation with the part already in the machine because its sensors help them to quickly determine which laser parameters will yield the best processing results. Quality assurance is immediate because the sensors show users how deep the microstructures are or the diameter of the holes drilled. In this way, contract manufacturers can hand the customer verified parts as soon as production is complete. The adaptable USP laser system can also be used for a variety of applications beyond surface structuring, including drilling and cutting by ablation.

COMPAMED.de; Source: Fraunhofer-Institut für Lasertechnik ILT