Displacement measurement is the measurement of changes in directed distance (

displacement Displacement may refer to: Physical sciences Mathematics and physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

). Devices measuring displacement are based on displacement sensors, which can be contacting or non-contacting. Some displacement sensors are based on displacement

transducers A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, measurement, and contro ...

, devices which convert displacement into another form of energy. Displacement sensors can be used to indirectly measure a number of other quantities, including deformation, distortion,

thermal expansion Thermal expansion is the tendency of matter to increase in length, area, or volume, changing its size and density, in response to an increase in temperature (usually excluding phase transitions). Substances usually contract with decreasing temp ...

, thickness (normally through the combination of two sensors),

vibration Vibration () is a mechanical phenomenon whereby oscillations occur about an equilibrium point. Vibration may be deterministic if the oscillations can be characterised precisely (e.g. the periodic motion of a pendulum), or random if the os ...

, spindle motion, fluid level, strain and

mechanical shock In mechanics and physics, shock is a sudden acceleration caused, for example, by impact (mechanics), impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation. Shock describes matter subject to extreme rates of for ...

. Displacement sensors exist that can measure displacement on the order of

nanometers 330px, Different lengths as in respect to the molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm), or nanometer (American and British English spelling differences#-r ...

or smaller.

Application

Displacement receivers can be used to study and observe the stress waves passing through a material after it is struck.Hsu, K., Cheng, C., Hsu, S., & Yu, P. (2022)
Rapid assessment of fire damage to reinforced concrete structures using the surface wave method with contact and non-contact receivers
International Symposium on Non-Destructive Testing in Civil Engineering (NDT-CE 2022), 16-18 August 2022, Zurich, Switzerland. ''e-Journal of Nondestructive Testing'' Vol. 27(9). https://doi.org/10.58286/27289 This can be used, for example, to assess fire damage in

reinforced concrete Reinforced concrete, also called ferroconcrete or ferro-concrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ...

. Displacement transducers are often used to measure vibration.. Excerpt accessed through GlobalSpec

Types

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 high-frequency sound waves and measuring the time they take to return. Displacement sensors can be made using linear variable differential transformers. Strain gauges can be used as the base for small displacement transducers on the order of 0 to 10 mm. In music, certain music keyboards can be considered to measure displacement 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 Polyphony ( ) is a type of musical texture consisting of two or more simultaneous lines of independent melody, as opposed to a musical texture with just one voice ( monophony) or a texture with one dominant melodic voice accompanied by chords ...

aftertouch capability. Polyphonic aftertouch is no longer a feature of presently manufactured keyboards, but certain older models such as the

Roland Roland (; ; or ''Rotholandus''; or ''Rolando''; died 15 August 778) was a Frankish military leader under Charlemagne who became one of the principal figures in the literary cycle known as the Matter of France. The historical Roland was mil ...

A50 featured a pressure sensing resistor, similar in principle-of-operation to a carbon microphone, in each key.

References

Transducers {{energy-stub