Introduction
In through-transmission laser welding of polimeric materials a focused laser beam is directed at
two overlapping thermoplastic parts: first designed to be transparent to the laser wavelength and a
second one, absorbent in IR spectrum. Between the laser beam and the components to be assembled
there is a relative motion which allows a continuously operating laser beam to irradiate a line of a
specific width. The heat generated by absorption is transmitted to the transparent component by
conduction. The bonding between the two components occurs by the interpenetration of the molecular
chains in this area. Since this phenomenon is very active in a "fluid" state of matter, the temperature at
interface has to be between the temperature of solid-liquid transition and the initial temperature of
degradation of the thermoplastic materials [1]. Comparing to the traditional welding techniques, the
laser welding efficiency is strongly dependent on the materials properties. In consequence, obtaining a
high-quality weld joint is conditioned by a good understanding of the material behavior under laser
irradiation, based on a clear identification and modeling of the optical and thermal phenomena
involved.
Concerning the optical phenomena, particularly the laser beam attenuation in polymers, there
are some experimental approaches for quantifying the influence of fillers, pigments, reinforcement