Intermittent curing and its effect on pulsed laser-induced photopolymerization

Different intermittent curing methods were conducted for pulsed laser induced photopolymerization reactions in a TMPTA acrylic system. Two methods of curing were compared, named grouped pulses impingement (GPI) and consecutively pulsed curing (CPC), respectively, in which the total number of the curing pulses were kept same. In GPI, a prominent light diffraction effect was observed in the post curing process, but was absent in the CPC procedure. A condensed but limited sized core of polymeric structure was the cause of the light diffraction. The amount of inhomogeneity in the refractive index for the core was about 90% of the cured background. Simulations based on Fresnel diffraction theory were performed, and the result was in good agreement with the experimental observations. PACS 42.25.Bs; 61.82.Pv; 82.35.-x