Near-field plane wave generation using a minimum mean square error approach

Holographic techniques are being developed to obtain near-field target strength measurements. This concept requires a projector array in the near-field to produce approximate plane waves in the volume occupied by the target. A method has been developed to generate complex weights that are applied to the elements in the projector array as amplitude shadings and time delays. This paper shows how a rectangular volume surrounding the target is a Hilbert space, and uses the classical projection theorem to obtain the optimum weights in the mean square error sense. Performance curves indicate the usefulness of this method.<>