The gradient index (GI) plastic rods were successfully fabricated by the interfacial gel polymerization technique. The UV/vis absorption spectra were used in this study as a new measure method for assessing the distribution of bromobenzene at PMMA base rod. For the comparison, a York P101 profile analyzer was used for measuring refractive index distribution of the preform. The results suggested that electronic absorption spectra could be used as a simple and available method for the measurement of the profile when a suitable dopant was used.
