A displacement receiver, also known as a displacement sensor, displacement transducer, or displacement gauge, is a device that responds to or is sensitive to directed distance (displacement).
Displacement receivers can be used to study and observe the stress waves passing through a material after it is struck.[1] This can be used to assess fire damage to reinforced concrete.
Displacement transducers are often used to measure vibration.[2]
Displacement transducers are displacement receivers. Displacement transducers measure the distance between a sensor and a target. They are sometimes and sometimes not in contact with a target.
Optical displacement sensors exist, using reflected light to determine distance.
An ultrasonic displacement sensor is a kind of displacement sensor. These measure the distance to targets by emitting low-frequency sound waves and measuring the time they take to return.
Displacement sensors can be made using linear variable differential transformers.
Examples of displacement receivers include carbon microphones, strain gauges, and pressure sensors or force sensors, which, to within an appropriate scale factor, respond to distance.
In music, certain music keyboards can be considered displacement receivers in the sense that they respond to displacement, rather than velocity (as is more commonly the case).
Examples of displacement-responding sensors include the mechanical action of tracker organs, as well as the force-sensing resistors found in music keyboards that had polyphonic aftertouch capability. Polyphonic aftertouch is no longer a feature of presently manufactured keyboards, but certain older models such as the Roland A50 featured a pressure sensing resistor, similar in principle-of-operation to a carbon microphone, in each key.