Ultrasound transverse flow measurement with high lateral resolution

Transverse flow measurement with high lateral resolution is demonstrated. The technique is based on collection and cross-correlation of signals scattered from two adjacent ultrasonic foci that are formed by a newly developed dual-beam acoustic lens. The lateral resolution for flow measurement is primarily determined by the separation of the focal spots. The authors present models and simulations based on both geometrical acoustics and diffraction that predict the behavior of the dual-beam lens. A 4.5-MHz flow measurement system has been constructed; the measured separation between the focal spots in this system is 2 mm, in good agreement with design and simulations. Preliminary results obtained from flow velocities in the 50- to 100-cm/s range in a 6-mm diameter tube are presented