ARIADNE is a 1-ton two-phase liquid argon (LAr) time projection chamber (TPC) featuring a novel optical readout. Four electron-multiplying charge-coupled device (EMCCD) cameras are mounted externally, and these capture the secondary scintillation light produced in the holes of a thick electron gas multiplier (THGEM). Track reconstruction using this novel readout approach is demonstrated. Optical readout has the potential to be a cost effective alternative to charge readout in future LArTPCs. In this paper, the technical design of the detector is detailed. Results of mixed particle detection at the CERN T9 testbeam (representing the first ever optical images of argon interactions in a two-phase LArTPC at a beamline) and cosmic muon detection at the University of Liverpool are also presented.