THE CHARACTERIZATION OF OPTICAL RESISTANCE OF PLASTICS AND POLYMERIC COMPOSITES AT 1.06-MU-M

The procedure for measuring the optical resistance of polymeric materials in single- and multiple-phase tests is considered. The ambiguity of resistance characterization by the introduction of threshold radiation parameters which do not take into account the cumulative nature of laser induced destruction is shown. The experimental data indicating the existence of a "safe" light intensity for any number of pulses are presented. The results are explained by means of a model which suggests that the dependence of the number of pulses needed for breakdown the radiation intensity is caused by the process of accumulation of stable elementary defects nucleated from structural inhomogeneities ("weak points") of a polymeric matrix. The "safe" power density of laser pulses in a multiple-shot test is an objective characteristic of the optical resistance of the material.