Optimal transmit/receive beam synthesis for coded-excitation pulse-echo imaging

Criteria for optimal synthesis of transmit/receive beams with code-fed arrays for pulse-echo imaging are addressed. It is shown that careful design of transmit/receive beamforming is necessary to produce uniform illumination of the region of interest to allow parallel processing of multiple image lines for improving the data acquisition rate. Furthermore, it is shown that the uniform illumination of the ROI is necessary to produce robust reconstruction filters with acceptable point-spread functions (PSF). In this paper, we introduce a discrete Fourier transform (DFT) based method for computing the (regularized) postbeamforming reconstruction filters and their associated PSFs. This new tool greatly facilitates the investigation of transmit/receive beam forming strategies with code-fed arrays. It is shown that the DFT-based PSFs are excellent predictors of the performance of the filter-based image reconstruction from speckle-generating media.