A method for measuring flow velocity distribution in the interior of a transparent fluid is proposed. The method utilizes a thin sheet of laser light, which illuminates fluid containing small scattering particles. A double-exposure hologram is made with the scattered light as a signal wave. In the reconstructed image we can observe interference fringes which correspond to the distribution of particle displacements between the two exposures and consequently to the distribution of flow velocity. Simple experiments were performed that confirmed the usefulness of the method. A discussion of the relation of this method to laser Doppler velocimetry shows that the two methods utilize different aspects of the same phenomenon.
© 1977 Optical Society of AmericaPDF Article