A technique for measuring velocity gradients in laminar flows by homodyne light
scattering is presented. A theory which describes the light-scattering spectrum is
derived that includes the effects of different types of linear flow fields, particle diffusion
and the intensity profile in the scattering volume. The conditions which must be
satisfied in order that the theory describe the experimental situation are outlined and
complementary experiments are performed which both verify the theory and apply
the technique. Verification is provided using the flow in a Couette device, and the flow
due to single rotating cylinder in a large bath of fluid. The technique is then applied
to measure the spatial variation of the shear rate in a four-roll mill
