In modern society, touchscreen panels are widely used as display components in various advanced devices such as smartphones, tablet PCs, and laptops. With the widespread adoption of portable smart devices for personal use, the demand for touchscreen panels has increased significantly. To function effectively as display components, touchscreen panels must exhibit optical characteristics such as high transmittance and low reflectance.
Currently, touchscreen panels are manufactured using a full-lamination process with optical adhesives. In such structures, optical adhesives not only serve to bond individual layers but also play a crucial role in determining the optical and electrical performance of the panel. In particular, a large refractive index mismatch between the optical adhesive and the laminated glass leads to increased internal reflection, resulting in degraded visibility and increased power consumption. Therefore, precise measurement of the refractive index of the adhesive layer within laminated glass is essential for improving touchscreen panel performance.
In this study, we propose a method for measuring the refractive index of the adhesive layer in laminated glass for touchscreen panels using a spectral reflectometer. The reflectance spectra acquired from the samples were analyzed using a model-based approach to simultaneously determine the refractive index and thickness of the adhesive layer. Measurements were performed on two types of specimens composed of different adhesives and laminated glasses, and the results were compared with those obtained using other optical refractive index measurement instruments.
This study provides fundamental data for evaluating the optical performance of touchscreen panels and is expected to contribute to the development of refractive index measurement techniques for various optical materials with complex structures in future research.
