Ultrasonic sensors work similar to radar or sonar. Ultrasonic
sensors send out high frequency sound waves and depending on the echo that is received back by the
sensor, it calculates the distance or simply the presence of an object. Ultrasonic sensors have an
advantage over optical sensors because the sound wave they emit will work under dust, dirt, fog and
bright light where as an infra red detector could miss read when dust or dirt accumulates on the lens.
This technology is especially useful for modern manufacturing processes, for operations such as
counting objects as they move along a conveyor or measuring fluid as it is filled into a container.