Controlling the sound beam of an ultrasonic sensor

To efficiently detect an object behind a thin plate through a small hole with an ultrasonic sensor, where the ultrasonic beam is too wide for the hole, ultrasonic waves can be focused or guided to better pass through the small hole. One possible method of influencing the ultrasonic beam is the use of cylindrical ultrasonic waveguide so-called sound tubes. A sound tube is an ultrasonic waveguide, i.e. a structure or medium that guides and limits the propagation of high-frequency sound waves. The waveguide helps to control the path of the ultrasonic waves and prevent them from propagating or attenuating along their path. By confining the sound waves within the tube, a narrow beam is created which improves the ability to focus on specific targets and reduce interference from surrounding objects. When designing an ultrasonic waveguide, materials, dimensions and acoustic properties must be carefully considered to ensure minimal losses due to absorption and scattering from the walls. In practice, sound tubes are realized in a way that their shape and length are precisely matched to the ultrasonic frequency of the transducer of an ultrasonic sensor. By carefully selecting the frequency and controlling the alignment of the sensor, combined with a sound tube, the effects of interference can be minimised, and more accurate and reliable measurements can be made. Other possible applications for sound tubes include level measurement in tubes with very small diameters, for example in filling systems in medical technology. When sensors are arranged very close together, for example in arrays for height profile monitoring, sound tubes suppress multiple interference disturbances in addition to synchronizing the sensors on the control side.

Continue to the sound tubes of P43 sensors

Use of the BS-M12-ST with a P43-25-M12-U-CM12.

In order to be able to detect objects or fill levels through an 8 mm hole in the example, a sound tube (right in the picture) is required, as the sensor interprets the sound waves reflected by the surface around the hole as the first object without this focusing aid. Only the limitation by means of a sound tube allows a measurement through the 8mm small, round opening.