Abstract: A system of double-pulse particle velocimetry, according to which small scattering particles are illuminated by two short pulses of laser light and then images are recorded photographically to produce a record from which the particle velocity can be determined by measuring the displacement of the particle images. Particle images is understood to mean both the non-overlapping individual particles and overlapping, coherently interfering images commonly referred to as "speckle". In order to resolve the directional ambiguity inherent in the system, artificial shifting is effected in the image field between exposures by an amount that is greater than any negative displacement occurring in the field, such shifting being performed here by means of an electro-optical device in place of the shifting previously produced by rotating mirrors and the like.