Vibration assisted femtosecond laser machining on metal

We demonstrate a novel approach to improve laser machining quality on metals by vibrating the optical objective lens with a frequency (of 500 Hz) and various displacements (0–16.5 μm) during a femtosecond laser machining process. The laser used in this experiment is an amplified Ti:sapphire fs laser system that generates 100 fs pulses having an energy of 3.5 mJ/pulse with a 5 kHz repetition rate at a central wavelength of 790 nm. It is found that both the wall surface finish of the machined structures and the aspect ratio obtained using the frequency vibration assisted laser machining are improved, compared to those derived via laser machining without vibration assistance. This is the first report of low frequency vibration of an optical objective lens in the femtosecond laser machining process being exploited to obtain significantly improved surface roughness of machined side walls and increased aspect ratios.

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► The experimental setup of vibration-assisted femtosecond laser machining system.
► The wall surface finish of the machined structures using the vibration assisted laser machining is improved.
► Compared to laser machining without vibration assistance.
► Aspect ratio got using rate vibration assist laser machining are better, compare to laser machining without vibration assist.