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INTRODUCTION
Lasers are being increasingly used in polymer science due to the distinct
advantages of these powerful sources of radiations. The spatial coherence of the
laser emission provides a great directivity, which permits one to focus the laser beam
down to a submicronic spot. The temporal coherence of the laser emission, which
occurs at a well-defined wavelength, reduces the extent of undesirable, secondary
reactions induced bypolychrornatic radiation, while it allows at the same time 'a
precise'co'ntrol of the penetration profile. Thelarge pbwer output that is concentrated
in a very, narrow beam leads to extremely high light-intensities, thus increasing
drastically the overall rate of the photochemical process considered.
Since our earlier work on laser-induced photopolymerization, which
demonstrated that acrylate resins can be cured quasi-instantly by UV laser
irradiation, several applications of this advanced technology have appeared in
various industrial sectors. The direct writing of high-resolution relief patterns by
means of a computer-ordered laser beam is used in micro-lithography to produce
printing plates (Hoechst) or 'masks forthe fabrication of integrated circuits (AU). In
stereolithography, sophisticated 3D objects are created by laser-induced curing of
successive layers of a liquid acrylic resin, in a fully automated process (Japan
Synthetic Rubber, 3 D Systems)., Recently, laser-sensitive multifunctional acrylate
films have beenused to produce large dimension hologramsby a dry process,
which has the great advantage of requiring rio further treatment after the laser
exposure (Dai Nippon Printing)
In this paper, the outstanding performance of laser-induced curing is illustrated
by two examples which show how this technology can both provide some basic
information about the curing mechanism of multifunctional acrylates, and lead to
promising new applications in optoelectronics. We also described here an analytical
method, based on pulsed irradiation, which a!lows one to rapidly test the reactivity of
UV curable formulations, and thus evaluate the efficiency of new photoinitiators and
monomers.
