The Stirling cycle has thermodynamic reversibility. Its main disadvantage has been the need for high-pressure, sliding piston seals. This is much higher than any previous thermoacoustic engine. The interaction of light and sound can produce many effects and devices. Optoacoustic modulators can bend laser light.
Laser beams can generate and detect acoustic waves.
By controlling the position and size of a laser beam array, the points of ultrasound generation and detection are moved and an ultrasonic image is constructed. This enables tissues to be sampled without removing them from the patient. Sound is produced from a sudden local compression of a gas, liquid or solid. An ultrasonic transducer is a device that changes its physical size when an electric potential is applied to it. At an interface there is reflection, transmission and absorption.