GENERATION OF SINE-WAVE BY A ONE-DIMENSIONAL ARRAY FOR APPLICATIONS IN ULTRASONIC-IMAGING

A new solution to the 2-D scalar wave equation is presented which desc ribes an ultrasonic beam maintaining the lateral field response expres sed by the sine function over a finite depth of field, This new beam i s realizable with a linear array transducer, and less subject to diffr action spreading than conventional focused beams, Physically, it is a superposition of plane waves having the same wavelength, but traveling at different angles. It is shown by numerical simulation that the bea m can provide more uniform lateral beamwidth and smoother on-axis fiel d magnitude over a greater depth of field than the rectangular transdu cers and Gaussian apodized transmitters which have been used to increa se the limited depth of field of the conventional focused beams, Compa red with currently developed limited diffraction beams which must be g enerated by 2-D array transducers, the beam has a wider lateral beamwi dth but with lower sidelobe levels, In ultrasonic medical imaging, the beam enables one to obtain a line focus using a 1-D array transducer and to eliminate the diffraction correction required in some applicati ons such as tissue characterization.