  Neutrino experiments often use large volumes of water, organic scintillators
or noble liquids as active detection material. Due to the large hydrostatic and
buoyancy forces involved, precise knowledge of the liquid levels inside the
detector tank are mandatory. Here we present the main characteristics of the
TruSense S310 Laser Range System. Level measurements can be performed without
direct contact to the liquid and through a gas-proof acrylic window, thus
preserving the strict radiopurity and chemical requirements of the target
liquid. We report the results of a suit of laboratory experiments for
short-term precision tests ($\pm$5\,mm) and long-term stability studies.
Moreover, we demonstrate that the infrared laser can be used while standard
bi-alkali PMTs are operational. We discuss the mechanical layout and
integration of the system in the OSIRIS pre-detector that will monitor the
radiopurity of the liquid scintillator for the large-volume neutrino experiment
JUNO.
