Excellent micro-machining with brass and aluminium are being claimed for a picosecond laser system, based on fibre lasers and developed by a team led by Laser Zentrum Hannover.
Industry has put a long list of requirements on micro-machining laser systems – the beam must be easy to focus and non-fluctuating, while the need for beam re-alignment has to be minimal. Machines must also be compact, capable of being placed close to the workpiece, yet not susceptible to harsh production environments.
Fibre-based picosecond lasers, which replace solid-state, free-beam laser set-ups – the result of the PULSAR (PUlsed Laser System with Adaptive Pulse PaRameters) research project – fulfil these requirements.
The system is adaptable to different settings, not least because the laser oscillator and amplifier are separate. Also, depending on the material and the process requirements, the repetition frequency and average output are easy to change – making rapid optimisation feasible.
In this system, a laser diode with a wavelength of 1,03µm and a pulse length of 40ps serves as the pulse source. Pulse repetition rate is flexible between 50kHz and 40Mhz. Using a three-step amplifier, the pulse can be amplified from several 10µW to an average output of 14W – meaning that, at a repetition rate of 1MHz, pulse energy is 14µJ.
Meanwhile, the fibre system shows good beam quality, and is resistant to production problems, such as dust contamination, temperature fluctuation and vibration. It is also smaller and less expensive than conventional solid-state lasers.
PULSAR is subsidised by the BMBF initiative INLAS (Integrated-optical Components for High-power Laser Sources, FKZ: 13N9685). PicoQuant, InnoLight, LPKF Laser & Electronics, Cicor Microelectronics and Alltec FOBA Laser Marking + Engraving are also involved in the project.
