Abstract: A linear transducer array with low overall side lobe sensitivity for use in steered beam imagers has a different interelement spacing for transmit than for receive, and preferably has a shorter transmit array with elements spaced at one-half wavelength as the center portion of a longer receive array whose unit elements are spaced at a full wavelength. Two or more elements in the center portion can be coupled together to a receiving channel to maintain constant spacing for the receive aperture in a 100% active transducer.

Abstract: A B-scan ultrasonic imager produces a rectilinear image and has a linear transducer array with only one switch per element. Individual elements or overlapping transmit subarrays are selected sequentially to generate pulses of ultra-sound. Received echo signals are sequentially sent down a long shift register delay line, are tapped off at the pulse repetition rate, and delayed by different amounts in the several channels and summed to effect time delay focusing of the echoes. The video output signal is post-processed to improve the TV monitor picture; interpolated image lines are conveniently derived with this architecture.

Abstract: An ultrasonic imaging system for medical and industrial applications produces quantitative acoustic impedance distributions from reflection data. The method and scanner apparatus with analog computation circuitry herein described acquires echo pulses reflected from impedance discontinuities in the specimen and computes impedance projections. The ensemble of projections, as in other computerized tomography systems, is used for reconstruction of the images which in this case are impedance distributions in a thin slice of the specimen.