IMPROVED ULTRASONIC DENSITY SENSOR WITH REDUCED DIFFRACTION INFLUENCE

The density of liquids can be measured with ultrasonic techniques. An important factor limiting the accuracy of the measurement is the effec t of diffraction of acoustic waves in the transducer. This paper prese nts a method to minimize such effects. A simple geometric model is use d to analyse the contributions of plane waves and diffraction waves as a function of the sensor geometry. Calculations using the model lead to an optimized sensor geometry where diffraction waves do not interfe re with the measurement signals. To demonstrate the fundamental improv ement of accuracy, selected measurements of optimized and non-optimize d sensors are compared. (C) 1998 Elsevier Science S.A. All rights rese rved.