Quantitative real-time pulsed Schlieren imaging of ultrasonic waves

Abstract

A pulsed Schlieren system based on Raman-Nath scattering by ultrasonic waves in water is described. High powered, monochromatic infrared pulsed light is used in conjunction with axial optics and a video camera to visualize the acoustic field. Projection beam profiles in any plane parallel or orthogonal to the direction of acoustic propagation are demonstrated. Controlled delay between acoustic pulse and light flash allows scrutinizing wave fronts at variable delay after launching. The method is applicable with reasonable repetition rates to broadband acoustic pulses with intensities in the medical diagnostic range. Quantification of the pressure density by analysis of the video signal is shown using a single-point calibration against a total acoustic power measurement by the force balance method, without a priori assumptions about the beam structure.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>