Together with six industrial partners, the Laser Zentrum Hannover e.V. (LZH) has developed a picosecond laser system based on fiber lasers. This system has achieved excellent micro-machining results for brass and aluminum. Up to now, solid-state lasers have been used for metal micro-machining. These systems are usually based on free-beam set-ups, which are easily brought out of alignment. Since the laser systems need water cooling, they are relatively large and difficult to integrate into the production line. The newly developed, fiber-based picosecond laser system fulfils all the requirements for industrial use. It is the result of the research project PULSAR (PUlsed Laser System with Adaptive Pulse PaRameters).
This system is especially flexible and adaptable to different settings because the laser oscillator and amplifier are separated. Depending on the material and the desired process results, the repetition frequency and the average output can be easily adapted to the current process.
A laser diode with a wavelength of 1,03 µm and a pulse length of approximately 40 ps serves as the pulse source. The pulse repetition rate is highly flexible, and can be set between 50 kHz and 40 Mhz. Using a three-step amplifier, the pulse can be amplified from several 10 µW to an average output power of 14 W. At a repetition rate of 1 MHz, a pulse energy of 14 µJ is possible.
The fiber-based, picosecond laser system has an excellent beam quality and is resistant to difficult production environments, such as dust contamination, temperature fluctuation or mechanical vibrations. Also, very good results in working aluminum or brass have been achieved. Furthermore, the system is smaller and less expensive than conventional solid-state lasers, according to the LZH. Among the many fields of applications are marking aluminum, making stamps of hard metal (V70) and stamping coins.Yvonne Klöpping