Curvature radius testing of optical lens based on autofocusing technology

An autofocusing-technique-based method for rapid and accurate non-contact measurement of radius of curvature (ROC) of optical lens is designed. The autofocusing is performed on the lens vertex and in the center of curvature respectively, and the distance between these two positions is ROC. The autofocusing technology is improved for the application of ROC measurement of optical lens: the connected region extraction is used to label the target image, and the sensitivity of sharpness evaluation function is improved; the searching strategy, i.e. the traditional hill-climbing method, is improved by meancomparison and 3-point method. The experiments validate the autofocusing-technique-based ROC measurement, and the accuracy is better than 0.2%, the repeatability is better than 0.109%. This approach has been applied to a optical lens ROC test station successfully.