A single‐beam Doppler interferometer is described, whereby light scattered by the diffuse target at slightly different directions interfere, producing a differential Doppler frequency which is much smaller than the Doppler shift of either beam. Due to the diffuse nature of the light scattered by the target, the conditions for alignment of the interferometer must include the effects of speckle decorrelation caused by both longitudinal and tilting motions of the target. Error sources, both systematic and random, are discussed. Ways to minimize the systematic error stemming from uncertainty in the actual direction of the motion, are discussed. The interference signals are processed digitally to minimize the effect of random errors, which can be reduced typically to 8% for the acceleration period and to a negligible degree for the constant velocity phase of the motion. A special exploding‐foil accelerator was constructed to test the new measurement scheme. Experimental results show repeatable measurements of velocity profiles up to about 0.4 mm/&mgr;s.