Figure 3.
Buoyancy balance used for measurement of total acoustic power. The absorbing castor oil target is positioned in a cylindrical water tank by nylon wire holding the target at four positions, the wires attach to a hook on the underpan weighing mount of a digital balance. The HIFU transducer is attached so that no air is trapped on its surface and no contact is made between it and the wires supporting the target. The HIFU beam propagates into the castor oil target, in the direction shown, through an acoustically transparent membrane (not shown).