Using the two-dimensional Mie scattering technique measurements have been performed inside the piston bowl of a four cylinder VOLKSWAGEN 1.9 l DI Diesel engine. The engine was prepared for providing optical access. A new evaluation procedure was developed which allows additional information on the spray penetration in direction of the piston axis. Quantitative results have been obtained on the jet tip penetration and the spray cone angles of the jets. From liquid fuel distributions inside a laser sheet 5 mm below the nozzle an appearence frequency distribution (AFD) has been calculated, which gives a quantitative statistical information on the liquid fuel distribution inside the light sheet plane with high local and temporal resolution. By means of the AFD the jet penetration in direction of the jet axes can be reconstructed in good approximation. The information provided by the AFD is also very suitable for the validation of results obtained by computer codes.