How pharmaceuticals act, how efficient catalysts are and how effective and accurate printing inks function all depend on the size of the nanoparticles they contain. However, there are as of yet no methods for monitoring the particle size distribution during grinding processes. In the EU-funded PAT4Nano project, a consortium from industry and research has spent the last four years looking for practicable approaches for such inline measurements. The Fraunhofer Institute for Laser Technology ILT in Aachen has developed a promising laser-based method that could soon make such measurements possible.