Modern methods based on population balance methods permit a fast and accurate calculation of important quantities within extraction processes. The approaches show a good correlation between experiments and simulations with a deviation of the Sauter diameter d(32) smaller as 5% (stirred vessel 450 mm) and 7-12% (column 450 mm). With the help of an optical measuring technique droplet swarms are examined transiently. The current limit of the transmitted light technique is at 16-20 vol.-% without further optimization. The limit of incident light technique is above 30 vol.-%. Distance transformation and watershed segmentation algorithms enable the analysis of the droplet images.