The ultrasound effect has been widely used in practice, mainly in the following aspects:

① The wavelength of ultrasonic inspection is shorter than that of general sound waves, with good directionality and the ability to pass through opaque materials. This characteristic has been widely used in ultrasonic inspection, thickness measurement, distance measurement, remote control, and ultrasonic imaging technology. Ultrasound imaging is a technique that uses ultrasound to present the internal image of opaque objects. The ultrasonic waves emitted from the transducer are focused on the opaque sample through an acoustic lens. The ultrasonic waves transmitted from the sample carry information about the illuminated area (such as the ability to reflect, absorb, and scatter sound waves), which are then concentrated on a piezoelectric receiver through the acoustic lens. The resulting electrical signal is input into the amplifier, and the image of the opaque sample can be displayed on the fluorescent screen using a scanning system.

The above device is called an ultrasonic microscope. Ultrasound imaging technology has been widely applied in medical examinations, used in the microelectronic device manufacturing industry to inspect large-scale integrated circuits, and in materials science to display regions and grain boundaries of different components in alloys. Acoustic holography is an acoustic imaging technique that uses the interference principle of ultrasound to record and reproduce three-dimensional images of opaque objects. Its principle is basically the same as that of optical holography, but the recording method is different (see holography). Using the same ultrasound signal source to excite two transducers placed in a liquid, they emit two coherent ultrasound waves: one beam passes through the studied object and becomes an object wave, while the other beam serves as a reference wave. The object wave and reference wave are coherently superimposed on the liquid surface to form an acoustic hologram. The acoustic hologram is irradiated with a laser beam, and a reconstructed image of the object is obtained by utilizing the diffraction effect generated by the laser reflection on the acoustic hologram. Real time observation is usually done using a camera and television.