Surface detection based on autofluorescence signal for three-dimensional measurement

This paper introduces the fluorescence response-based optical probing (FROP) method, a novel approach for the 3- dimensional (3D) measurement of precise products. While several established methods for 3D measurement exist, challenges remain when measuring precise products with small, smooth, and steep (3S) structures. Conventional techniques often struggle with these features due to limitations in capturing accurate optical responses from steep or overhanging surfaces. To address these challenges, this study proposes a surface detection scheme based on autofluorescence emitted from the sample surface. Unlike reflected light, which is directional, fluorescence is emitted over a wide angle, allowing for enhanced detection of optical responses from 3S structures. In the paper, the principle of the FROP method was proposed, and its performances were examined for surfaces tilted at varying angles. The results demonstrated that FROP could successfully detect vertical and even overhanging surfaces, underscoring its strong potential for 3D measurements. Finally, a full 3D structure was measured. Unlike confocal microscopy, which struggled with vertical surfaces, FROP successfully measured them. These findings validate the performance of FROP for precise 3D product measurements.