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  1. Ultrasonic sensors
  2. Technology

Many strengths, few limits: How ultrasound technology works

Ultrasonic sensors detect all sound-reflecting objects. To calculate the distance, they measure the time between sending and receiving a reflected sound signal. The target’s colour, transparency and surface reflectivity are irrelevant.

Comparison of ultrasonic sensors with other position sensing products

This chart rates the performance of various technologies with certain influences.

Ultrasonic Inductive Capacitive Photoelectric
Great distance to the object 1
Independent of colour / transparency 11
Independent of material
Temperature fluctuations
Deposits on the sensor 2 3
Extraneous light immunity
High ambient humidity


1) e.g. thin, clear-transparent film/glass
2) if not excessive
3) if non-conductive

Operating principle of ultrasonic sensors