An ultrasound transducer is designed to transmit high-frequency sound waves into a patient's body and detect the reflected pulses. The diagram below shows a simplified schematic of the key layers within the transducer.
Which of the following options correctly identifies the layers labeled AAA, BBB, and CCC, alongside their primary physical role in manipulating the wave behaviour?
A: Piezoelectric crystal (converts alternating voltage to mechanical vibrations); B: Backing material (absorbs excess heat generated during operation); C: Matching layer (maximizes wave reflection at the skin boundary to keep the energy concentrated)
A: Backing material (dampens the crystal oscillations to produce short pulses, improving axial resolution); B: Piezoelectric crystal (converts electrical signals to acoustic waves and vice versa); C: Matching layer (minimizes reflection at the boundary by having an intermediate acoustic impedance)
A: Acoustic lens (focuses the emitted waves to a specific focal depth); B: Piezoelectric crystal (sets up a stationary wave resonance to amplify signal strength); C: Backing material (minimizes thermal conduction to maintain constant wave speed)
A: Matching layer (ensures the frequency of the emitted waves matches the natural resonant frequency of tissue); B: Acoustic lens (prevents phase dispersion of the waves); C: Piezoelectric crystal (rectifies the incoming wave envelope)