Diffractive transducers for angle-independent velocity measurements

Usual Doppler (or equivalent) methods produce a value proportional to the product of flow velocity and the cosine of the angle between the flow and insonating beam. By using a diffractive transducer, multiple insonating beams can be obtained from one transducer, permitting multiple measurements, at known increments of angle, to be made. In effect, the conventional single equation in the two unknowns of velocity and angle, is, by using a diffractive transducer, replaced by two (or more) equations in the two unknowns, that can be solved for the velocity and angle. The theory and experimental verification of operation of diffractive transducers is presented. Diffractive transducers may enable simple and inexpensive hemodynamic monitoring