Sahar SohrabiMitra VesalHedieh PazokianMahmoud Mollabashi Physics Department, Iran University of Science and Technology, Tehran, IranPhotonics and Quantum Technologies Research School, NSTRI, Tehran, Iran h_pazokian@iust.ac.ir International Journal of Fundamental Physical Sciences (IJFPS) 8 2 74-78 June, 2018 2231-8186 https://doi.org/10.14331/ijfps.2018.330115 This study investigates the effect of pulsed CO2 laser irradiation on the optical properties and surface morphology of PMMA (poly(methyl methacrylate)). The samples were irradiated with a 9.55 μm CO2 laser, and their optical transmission, reflection, and refractive index were analyzed using UV-Vis spectroscopy. Scanning electron microscopy (SEM) was used to assess surface morphology changes. The results show that surface transmission generally decreases with increasing pulse number, while reflection and refractive index responses depend on fluence and pulse count. Below ablation threshold, radical formation was significant, while above threshold, surface microstructures and morphology changes played a key role in optical modifications. Pulsed CO2 laser, PMMA, Optical properties, Morphology https://creativecommons.org/licenses/by-nc/4.0/