The influence of temporal pulse length on laser induced PVD of diamond-like carbon (DLC) as well as Si and Cu films is investigated, using 30 ns and 500 fs UV laser pulses of 248 nm. For the case of the DLC films the laser generated plasma is analyzed by time of flight (TOF) and also by optical emission spectroscopy. The TOF measurements of ablated carbon particles exhibit striking differences between nanosecond and femtosecond laser irradiation. In the case of 30 ns ablation, cluster formation is quite evident in the TOF mass spectra, which coincides with the observation of micron-sized particulates on the deposited DLC films. No evidence for cluster formation is found in the TOF spectra obtained from the femtosecond plasma. The corresponding optical emission spectra indicate a high contribution of C+, rather than C2, and larger molecules in the nanosecond case. In addition, much higher kinetic particle energies (in the keV range) have been measured, which are known to be favorable with respect to DLC film formation. Consequently, high optical quality DLC films without particulates can be grown by femtosecond laser induced PVD. The differences of the two pulse durations are also discussed with respect to ablation characteristics, plume formation, and deposition rates.
I have to thank Industrial Laser Review for the invitation to
update you on the exciiner laser market. Two years ago Lindsay Austin
has given some examples of applications of use of industrial excimer
laser in particular. I'm not going to repeat that because you can
find them in the SPIE's proceedings of the last industrial laser
market seniinar. As mentioned before this afternoon we have hardly
heard anything about excimer lasers. It was only after until the
presentation of Jim Rutt where he explicitly mentioned excimer lasers
that triggered a few questions about excimer lasers. And one of the
reasons for that is that it gets lost in the noise of the statistics
and the uncertainties that we have heard this afternoon, and if I take
then the exciraer figures they hardly play a role. If I compare, for
instance, that I have heard something like 1000 CO2 and YAG laser
units sold in the U.S. in 1990, then you can intagine that when we talk
about industrial excirner lasers which are in the order of 80, less
than 100, you're completely in the noise of the other figures.
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