US 4,694,434 AGranted

Three-dimensional imaging system

OwnerOlaf T. von Ramm, Stephen W. Smithinventors

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Abstract

An acoustic pulse echo imaging system capable of producing an image of a three-dimensional object utilizing a two-dimensional display having perspective capabilities is described. In the system angular relationships of targets at all ranges are maintained for display. The system uses a two-dimensional transducer array of piezoelectric elements; the array is steered to assume transmit and receive orientations in both azimuth and elevation by producing (1) a directed transmit pulse and many similarly directed receive orientations or (2) a non-directed transmit pulse and many directed receive orientations. For each transmit pulse a parallel processing system produces several unique image points whose locations in the image correspond to the tangents of the angles of the receive orientations in the azimuth and elevation planes. The brightness of each image point is the weighted integral of the echo data received along each receive path. As an option, range discrimination capability is provided by means of a range dependent gain control, brightness shading as a function of range or a color display in which data originating from different ranges is displayed in different hues.

A radiated energy pulse-echo imaging system with transducers for transmitting pulse for producing an image of a three-dimensional object in a display having at least two dimensions maintaining perspective, in which, at all ranges, the angular relationships of all targets on the object relative to the origin of the transducers are reproduced in the display, comprising:

an array of transducers for transmitting pulses toward the three-dimensional object and receiving corresponding echo data,
means for steering said array in elevation and azimuthal directions to assume predetermined transmit and receive orientations relative to an initial array position, said array assuming a predetermined angular transmit orientation for each transmitted pulse and a plurality of predetermined angular receive orientations for each transmitted pulse, said array receive orientations being defined by angles formed in the elevation and azimuthal directions between said array in said initial position and said array in said receive orientations, processing means for receiving the echo data for each transmitted pulse from said array of transducers and for producing therefrom output signals indicating a plurality of image points having predetermined locations in the image to be displayed corresponding to the relative locations of those image points on the three-dimensional object,
means for storing values of said echo data to produce a brightness control signal for each said image point,
display means,
and means for communicating said image point output signals and said brightness control signals to said display means and for locating said image point in said display means at a location directly related to said angles defining said array receive orientations,
amplitude weighting means for varying the amplitudes of said image point output signals in relation to the distance from which said echo data are received, said weighted image point output signals being applied to z-axis drive means of said display means.

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Abstract

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