Patent ID: 7972271

Claim:
An imaging system, comprising: a) a plurality of subarrays, each having adjacent transducer elements, defining an array of transducers for transmission of energy in a plurality of transmit directions with at least one transmit focal length, for reception of responses to said energy and for output of receive signals; b) a subarray-dependent first filter for spectral modification and interpolation between scan lines for a plurality of receive directions, Q S , and receive focal lengths from each of said subarrays; and c) a unit for combining outputs from said first filter corresponding to each of said subarrays to produce an image; wherein a number of receive directions Q S1 in a first plane satisfies Q S ⁢ ⁢ 1 ≥ 4 ⁢ M 1 ⁢ d 1 λ min ⁢ sin ⁡ ( Θ 1 2 ) , where M 1 is a number of said adjacent transducer elements in a first dimension of each of said subarrays and said array, d 1 is a spacing between each of said adjacent transducer elements in said first dimension, λ min is a minimum wavelength in said transmitted energy, Θ 1 is a first sector angle in said first plane, and wherein an upsampling ratio L 1 in said first plane during interpolation in said first filter satisfies L 1 ≥ 4 ⁢ N 1 ⁢ d 1 λ min ⁢ sin ⁡ ( Θ 1 2 ) Q S ⁢ ⁢ 1 , where N 1 is a total number of said transducer elements in said array in said first dimension.