Fresnel-reflection-based fiber sensor for UV adhesive cure monitoring

A fiber-optic relative sensor for real-time UV cure monitoring is presented. Its operational principle is based on the density-dependent variation on the refractive index of materials along with the Fresnel reflections from the interface between the fiber end and UV adhesive. Both the experimental and theoretical analyses are investigated in detail. The experimental data of refractive indices are measured during the curing processes under different UV intensities, which can be fit with two-term exponential equations. As observed, it shows less time consumption with higher UV intensity. The time coefficients of the curing process are estimated and explained explicitly. The proposed cure monitoring sensor has a reliable and concise structure.