The familiar property responses of isopropylacrylamide hydrogel, cause the hydrogel to undergo a discontinuous volumetric phase across a critical level of stimuli. Poly(N-isopropylacrylamide) hydrogel is a recognized response to global temperature stimuli across the low critical solution temperature (LCST). The basic PNIPAM hydrogel undergoes its phase change at a LCST of 34°C, where water is expelled from the interior of the gel microsphere, as the temperature increases past LCST. The responsiveness of PNIPAM hydrogel offers the potential for controlling optical properties of a medium such as refractive index and scattering index. In the present work we present the refractive index of microsphere/microbeaded hydrogel structures necessary for optical application. The particle size of the hydrogels nanostructures at room temperature is observed to be 300-400 nm as estimated by dynamic light scattering and agree well with scanning electron microscopy measurements. The temperature dependent refractive index change of hydrogel microspheres have been measured using variable angle spectroscopic ellipsometry and shows a 10% change as the temperature changes from 33°C to 34°C.