Optical stamping enables fast and precise laser microstructuring

At the Fraunhofer Institute for Laser Technology ILT, in collaboration with RWTH Aachen University, researchers have developed a process known as optical stamping. The method uses a spatial light modulator (SLM) to shape the beam of an ultrashort pulse laser (USP laser) into a desired pattern and transfer it directly onto a workpiece surface. This approach eliminates the need for time-consuming surface scanning, significantly reducing processing times.

"The optical stamping process allows this problem to be circumvented," explains Sönke Vogel from the Micro and Nano Structuring Group at Fraunhofer ILT. "This creates microstructures that are precise, reproducible, and made in a fraction of the time previously required, with significantly less wear and tear compared to mechanical processes and without the need to retool the optics."

Unlike conventional laser machining, where a beam scans point by point, optical stamping forms the laser light into a complete structural pattern in a single step. The core element is an LCoS-based SLM (Liquid Crystal on Silicon), which modifies the phase front of the laser light with pixel precision. This allows the creation of deterministic microstructures tailored to specific technical requirements.

Paul Buske, from RWTH Aachen University’s Chair of Technology of Optical Systems (TOS), designs the phase masks that shape the laser beam using optical neural networks. "Thanks to established AI training methods, optical neural networks enable unprecedented flexibility in beam shaping," says Buske.

The software-controlled beam shaping enables quick adaptation of patterns without any mechanical adjustments. USP lasers with pico- and femtosecond pulses ensure high precision while minimizing thermal impact on the material.

The EU project METAMORPHA, conducted with partners such as thyssenkrupp Steel Europe, focuses on developing laser-based surface treatments that improve the quality and durability of flat steel products.

The potential of optical stamping extends to various materials and sectors. Possible applications include:

• Hydrophobic and antibacterial surfaces for functional coatings.
• Data matrix marking for improved product traceability in medical technology and pharmaceutical manufacturing.
• Microstructuring of ceramics and polymers for advanced surface functionalities.

"What makes optical stamping so special is the combination of speed, precision, and flexibility," adds Vogel. "We can adjust the structural pattern using software in a fraction of a second without having to mechanically reconfigure the optics."

COMPAMED-tradefair.com; Source: Fraunhofer Institute for Laser Technology ILT