Automatic microscopes for nuclear emulsion readout in high-energy and particle physics

Nuclear emulsions feature unequalled spatial precision and resolution (better than 1 micrometer) among the detectors used for high-energy and particle physics. They can be used to perform topological study of interaction and decays of subnuclear particles, but the traditional workflow is heavily manpower-dependent. The quick development of electronic devices in the ‘70s and ‘80s made them progressively obsolete. Starting from the ‘90s, with the development of machine vision, electronics and computers revamped the technique, and automatic microscopes appeared in Japan and Europe. Automatic 3D imaging was essential to conceive and carry out the new generation of experiments based on nuclear emulsions, combining very high statistics and high data quality. Concepts and detailed features of such microscope systems are reviewed in the paper, and an outlook is given of the probable evolution of technology in the field.