6 Industrial Laser Solutions MAY/JUNE 2015 www.industrial-lasers.com
Copper foil with a 1cm-long bar of 20 × 20µm2 cross-section was cut at 13mm/s without
any thermal distortion.
inverse square root of the pulse width, the
heat input per femtosecond pulse is much
lower than for longer pulses or continu-
ous-wave lasers. By means of an adapted
beam defection strategy, it is possible—
even for high pulse-repetition rates of sev-
eral hundred kilohertz—to keep the local
heat accumulation at levels suffciently low
to facilitate processing of thermally sensi-
Furthermore, non-thermal ablation in
the femtosecond range requires only low
pressures of a process assist gas, so there
is no risk that the gas fow deforms delicate structures.
Experimental cutting results
Flat copper and titanium sheets measuring
20 to 40µm thick were used to demonstrate
cutting of bars 20 to 100µm wide and 1 to
2cm long (FIGURE). Tests were performed
on a lab laser machining setup comprising
a 10W femtosecond laser (Jenoptik’s JenLas femto 10) and a galvanometer scanner.
Since the selected components are indus-try-proven, the results can be transferred
directly to industrial applications. Straight
cuts were made in single- and multi-pass
modes to fnd optimum ablation conditions.
The cut quality was evaluated by the sharp-