Quantitative Analysis of Droplet Evaporation Based on Wedge Prism Digital Holographic Microscope

This study presents a prism-based self-referencing digital holographic microscopy (PSDHM) system that utilizes a wedge prism. The front and rear surfaces of the prism have a wedge angle of 2°, which can reflect the parallel incident light, respectively, to generate a lateral displacement that varies with the propagation distance of the optical path. Focusing on the quantitative analysis of droplets, this innovative system effectively images water droplets and their dynamic evaporation processes. Results show that the evaporation process of water droplets undergoes three stages, each stage corresponding to a theoretical model. These are the constant contact radius (CCR) mode, the stick-slip (SS) mode, and the stick-jump (SJ) mode. Furthermore, by comprehensively analyzing the contact angle and the specific morphology of the droplet’s contact area, we revealed that the hydrophilicity of the cover glass influences the droplet morphology, contact area, and the evaporation process.