Ultrasonic electronic lens with reduced delay range
AssigneeThe Board of Trustees of the Leland Stanford Junior University
InventorAlbert Macovski
Life of this patent
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Abstract
Ultrasonic reflections are received by a transducer array whose resultant signals are passed through an array of time-varying delay lines to provide focusing at all depths. The delay lines are made up of a combination of two components, one increasing and one decreasing with the distance to the axis of the array. This combination minimizes the range of delay variations required over the depth range. When using charge coupled devices as delay elements, this combination minimizes the required range of clock frequencies.
Claims16
Apparatus for receiving ultrasonic reflections from an object comprising:
- a source of pulsed ultrasonic radiation which insonifies the object and produces a sequence of ultrasonic reflections;
- a transducer array for receiving the sequence of ultrasonic reflections and producing a plurality of transducer signals;
- a first focusing array of delay structures whose inputs are connected to the transducer signals and whose delay varies with the magnitude of the distance of each transducer to the axis of the array;
- a second focusing array of delay structurs whose inputs are connected to the outputs of the first focusing array of delay structures and whose delay varies with the magnitude of the distance of each transducer to the axis of the array in a manner opposite to that of the first focusing array of delay structures so that the sum of the delays from each transducer through the first and second focusing delay structures decreases with the magnitude of the distance to the axis of the array;
- means for adding the outputs of the second focusing array of delay structures to produce a focused signal;
- and
- means for utilizing the focused signal.
Apparatus for receiving ultrasonic reflections from an object comprising:
- a source of pulsed ultrasonic radiation which insonifies the object and produces a sequence of ultrasonic reflections;
- a transducer array for receiving the ultrasonic reflections and producing a plurality of transducer signals;
- a lens positioned adjacent to the transducer array, between the object and the transducer array, whose delay of the ultrasonic reflections varies with the magnitude of the distance of each transducer to the axis of the array;
- a focusing array of time-varying delay structures whose inputs are connected to the transducer signals and whose delay varies with the magnitude of the distance of each transducer to the axis of the array in a manner opposite to that of the lens so that the delay difference of each transducer signal compensates for the delay difference from each ultrasonic reflection, through the lens, to each transducer;
- means for adding the outputs of the focusing array of delay structures to produce a focused signal;
- and
- means for utilizing the focused signal.
Dependencies are inferred from the claim text.