Thereby, when the ST is on, the main ultrasonic field (emitted from the MT) propagates in water without bubbles (bottom sketch of Fig. 1), and the output signal (at the HP) is the same as the input signal: the switch is on (SON mode).
Thereby, when the ST is on, the main ultrasonic field (emitted from the MT) propagates in water without bubbles (bottom sketch of Fig. 1), and the output signal (at the HP) is the same as the input signal: the switch is on (SON mode).