A major reason to use ultrasonic sensors is their ability to recognize most materials and surfaces. Color is of no consequence and they can detect solids, liquids, or powders. Surface properties also have no effect on detection reliability. It does not matter if the surface is rough, smooth, high gloss, transparent, dirty, wet, or dry – a high-quality ultrasonic sensor delivers precise results.
The best reflection can be reached when level, smooth surfaces are positioned at right angles to the sensor surfaces. If the angle to the surface object is not 90°, the returning sound can be deflected away from the transducer, and it will no longer be detectable. Large angle deviations are possible when recording rough or uneven surfaces. The amplitude of the reflected ultrasonic signal must be high enough to allow reliable measurement. Similarly, high levels of dust and humidity reduce the acoustic energy and can reduce the maximum range of the ultrasonic sensor.