  The ARIADNE Experiment, utilising a 1-ton dual-phase Liquid Argon Time
Projection Chamber (LArTPC), aims to develop and mature optical readout
technology for large scale LAr detectors. This paper describes the
characterisation, using cosmic muons, of a Timepix3-based camera mounted on the
ARIADNE detector. The raw data from the camera are natively 3D and zero
suppressed, allowing for straightforward event reconstruction, and a gallery of
reconstructed LAr interaction events is presented. Taking advantage of the 1.6
ns time resolution of the readout, the drift velocity of the ionised electrons
in LAr was determined to be 1.608 \pm 0.005 mm/{\mu}s at 0.54 kV/cm. Energy
calibration and resolution were determined using through-going muons. The
energy resolution was found to be approximately 11 % for the presented dataset.
A preliminary study of the energy deposition (dE/dx) as a function of distance
has also been performed for two stopping muon events, and comparison to GEANT4
simulation shows good agreement. The results presented demonstrate the
capabilities of this technology, and its application is discussed in the
context of the future kiloton-scale dual-phase LAr detectors that will be used
in the DUNE programme.
