Three-dimensional measurement of structures with smooth-steep-surfaces using autofluorescence confocal signal

Autofluorescence-based three-dimensional measurement technique was developed. Structures with smooth and steep surfaces are difficult to measure with conventional measurement methods. In this study, we propose a new optical three-dimensional measurement method that uses fluorescence emitted by the object itself as a response signal. A theoretical model was proposed and validated for surface detection, and the model was in good agreement with experimental data and highly consistent with confocal microscopy results. Using the proposed method, we successfully measured a Blu-ray disc pick-up lens. The results demonstrated that the method could accurately measure steep slopes of up to 76° and vertical surfaces. These findings confirm the capability of the proposed method to measure structures with both smooth and steep surfaces effectively.