Ultrasonic linear position sensors and switches use ultrasonic waves in combination with light and frequency readings. Specifically, ultrasonic linear position sensors and switches use surface acoustic waves (SAW) and Lamb waves that reflect off the target. The distance between the ultrasonic linear position sensor and the target is calculated from the signal's return time and the propagation velocity of the measurement medium. Ultrasonic linear position sensors and switches are useful in environments that cause other sensing technologies to fail, such as dust, particle-laden air, moisture or wetness, or particularly arid conditions. When separated from their targets by a substantial distance, ultrasonic linear position sensors and switches are more accurate than other types of sensors.

