Interaction of a CuBr laser, operating at 511 nm wavelength and pulse duration of 30 ns with titanium wafers
was studied. It was investigated the efficiency of laser ablation, depending on the laser fluence, on the laser beam
scanning speed, and laser pulse frequency. The titanium surface modification was studied by scanning electron
microscopy (SEM) and XPS (X-ray Photoelectron Spectroscopy). Nanosecond laser irradiation of Ti led to the formation
of high porous granular structures consisting of agglomerated small micro- and sub microparticles.
The use of lasers in materials processing is an increasingly attractive choice for high technology manufacturing. Factors influencing the laser ablation process include laser beam parameters, such as wavelength, energy or fluence and pulse length, the material properties of the target, such as melting temperature, thermal diffusion rate, optical reflectivity, and the ambient gas.
We investigated the influence of laser treatment on titanium wafers with CuBr laser (&lgr;=511nm) by scanning laser beam with distance between paths 20&mgr;. The laser fluence varied from 4.7 J cm<sup>-2</sup> to 13.5 J cm<sup>-2</sup> and the laser beam scanning velocity from 25mm/s to 100mm/s with duration of 30 ns. The experiments were done in two kinds of ambient atmosphere: air and argon.
The morphology of the irradiated surface was studied by scanning electron microscopy (SEM). SEM study showed that the laser irradiation caused a change in the surface morphology due to the processes of melting and subsequent resolidification as well as particle deposition from the vapor plume.
The chemical state and composition of the irradiated titanium surface were determined using the Ti2p and O1s binding energy values and O/Ti intensity ratio. The XPS results indicated that on the irradiated titanium surface is formed oxide layer with stoichiometry close to TiO<sub>2</sub>. It was found that the ambient atmosphere is responsible for the change in the microstructure and chemical state of the titanium target.
It has been demonstrated that the Copper Bromide Laser is a promising tool in the micro-machining of several materials (Al, Cu, Brass, Si). These results were achieved with the combination of high average laser power, short pulses, visible radiation, high repetition rate and close to the diffraction-limited beam divergence. The heat-affected zone (HAZ) was relatively small and depends from the cutting speed and number of repetition.
In the present paper the possibility of the Copper Bromide (CuBr) laser as an attractive tool in the micromachining of different materials has been demonstrated. High-quality percussion drilling, trepanning, scribing, and precision cutting were demonstrated on metals and ceramics with a negligible heat affected zone (HAZ). These good results were achieved with the combination of high power, short pulses, visible radiation and close to the diffraction-limited beam quality.