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Abstract

A schlieren densitometer was constructed in which a new technique of beam def1ection. measurement was employed. In conventional systems, the schlieren deflection of a probing light beam is measured by a knife edge technique. In the experiment described here, the knife edge was replaced by a neutral density wedge. This innovation brought several advantages, the main one being the elimination of problems due to diffraction. The beam intensity, attenuated by the wedge, was monitored by a photomultiplier. The output voltage of the photomultiplier was time integrated to give a linear analogue signal for the density profile of a moving object or medium. The device was applied to the measurement of the density change across the shock front of a Mach 9 plane shock wave in argon. The results were in satisfactory agreement with values calculated from shock wave theory.