Estimation of radius of curvature using reflected-spot method

This paper presents a non-contact reflected-spot method (RSM) for estimating the radius of curvature (ROC) of smooth samples. The size of the laser spot reflected by the sample was used as the basis from which to calculate the ROC. A geometric model of the proposed RSM system was fabricated and experimental results demonstrated the efficacy of this approach in measuring the ROC of convex-plano lenses. The introduction of a correction factor reduced the system percentage error to 3~6%. Compared with traditional contact-based methods, the RSM system provides a non-invasive, rapid, portable, low-cost solution to the difficulties involved in measuring ROC.