Crossed beam ultrasonic flowmeter

Abstract

A crossed beam ultrasonic flowmeter particularly suited for measuring two dimensional arterial blood flow has two pairs of ultrasonic beam transmitting transducers the beams of which are focused to intersect at a predetermined region through which dynamic particles undergoing velocity analysis are moving. The transducers are preferably coplanar and disposed equiangularly about an axis with the predetermined region located therealong. A receiver is disposed adjacent the axis intermediate the beams for receiving the Doppler shifted scattered signal. Following squaring of the scattered signal, bandpass filters separate the spectrally separated scattered signals resulting from the two pairs of transducers which then undergo spectral analysis to determine the necessary frequency and velocity information. One of the four transducers may be utilized as a second receiver to determine the third velocity component with a filter separating the scattered signal resulting from the transducer disposed diametrically across the axis. Alternatively, a fifth transmitting transducer and second receiver are disposed on opposite sides of the axis with a filter separating the scattered signal resulting from the fifth transducer. A pair of perpendicular linear B-mode scanning transducer arrays intersect at and extend perpendicularly to the axis for obtaining sagittal and transverse B-mode images of a conduit carrying particles undergoing velocity analysis.