Optimization of beams with nonspherical extended depths of focus for reconfigurable 2D arrays

The flexibility of reconfigurable 2D arrays allows us to utilize various beamforming techniques with a limited number of channels. We investigated a different beamforming technique incorporating spherical and axicon focusing to attain an extended range of focus in the transmit beam. In this paper, we develop and optimize this hybrid beamforming technique for balance between range and image quality. A local minimization technique is discussed and four apertures chosen to cover a 4.5 cm depth for breast imaging were compared to pure spherical beams via PSF and CNR calculations. Improvements were statistically significant at focal depth extremes.