The innovation of ultra-fast laser material processing technology can promote the application of ultra-fast laser technology in consumer electronics and other industrial fields. At present, the industry has a large number of ultra-fast lasers over 100W, which can greatly expand many processes.

But the challenge now is to develop new beam guiding and process concepts to achieve large function output on the surface of the workpiece. At present, the main limitation is the technology: the laser system with high repetition rate needs a scanner with a speed of up to 1000 m/s, while the laser system with high pulse energy needs a new concept of beam splitting and forming to achieve the distribution of pulse energy.

Multi-beam concept

One option for better utilization of pulse energy is the concept of multiple beams, which involves splitting a laser beam into many sub-beams. Since 2012, a team from the Fraunhofer Institute of Laser Technology ILT has been working on this technology (multi-beam). Since then, experts have learned how to use Diffractive Optical Elements (DOE) to target more than 200 sub-beams in micron and nano-structures to obtain accurate results in the sub-micron range.

For the DOE, they use wet chemical etching to etch the structured surface of glass with high accuracy. Therefore, the static beam distribution of DOE is more accurate and durable than the dynamic beam forming method based on liquid crystal modulator.

In order to process materials effectively, laser beams are converted into beam matrices with many parallel wavelet beams by DOE. Using the scanner system and the f-theta optical system, small parallel beams can be focused on the workpiece, and can move simultaneously along all possible paths on the workpiece.

The drilling speed of precision holes can reach 12,000 per second.

Multibeam technology proves its value in drilling holes on metal films with thickness ranging from 10 to 50 microns. Traditional methods such as etching require preparation and rework, whereas laser drilling does not require these processes. Multibeam technology is suitable for periodic structures and requires smooth and flat surfaces.

In the micro-drilling process, the team of the Fraunhofer Institute of Laser Technology has achieved extremely high accuracy. With the new multi-beam system, Aachen's experts can achieve precise holes less than 1 micron in diameter. The spacing between holes can be reduced to several microns. To improve throughput, they used DOEs that could generate more than 200 sub-beams. In this way, they can handle more than 12,000 holes per second, each with an outlet diameter of less than 1 micron.

The current goal of the research team is to further improve drilling speed without affecting drilling quality. In the near future, the drilling speed is expected to reach 20,000 drills per second.