**4.6 Optical properties**

The impact of particle treatment on nanocomposite substances is very important. The *in situ* sensitization of alumina nano-sized particles dispersed in Methyl methacrylate resin and successive polymerization incorporates a better level of optical transmission at near-infrared exposure than untreated Al2O3. Experiments have found that the gold nanoparticles (AuNPs) when incorporated on polyethylene oxide/ polyvinyl pyrrolidone (PEO/PVP) components show an increasing trend of AuNPs to combinations of visual parameters tha increases urbach strength, and optical power gap is also raised.
