Pattern — and Amplitude — Optimization Of Random Sparse 2-D Transducer Arrays for 3-D Electronic Beam Steering and Focusing
Two dimensional (2D) ultrasonic arrays provide the possibility of three dimensional (3D) electronic focussing and beam-steering and thus 3D imaging. To prevent grating lobes in the array response, it is necessary to fulfill the.λ/2-condition in element spacing.1 The focusing depth of a transducer is determined by the relation (D/λ) of aperture size D and the wavelength λ. The axial and lateral resolution is determined by the inverse of this factor and the beamwidth of the ultrasonic signal.2 For focusing and beam steering in medical imaging in the lower frequency range a (D/λ)-factor of 30 up to 50 is necessary. For a fully sampled 2D-array this will result in a number of 3,600 up to 10,000 elements and electronical channels. Using existing technologies, the fabrication and implementation of such arrays and the beamforming electronics is not possible.
KeywordsMain Lobe Beam Pattern Transducer Array Ultrasonic Signal Dense Array
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