We will measure the displacement and detect the object position sensors become micro displacement sensor. Measuring two object space relative distance of the sensor was also seen as micro displacement sensor. Could be divided into two types: contact and non-contact displacement sensors. Contact type displacement sensor, conduction and the measured body together, then the position of the conduction rod signal into electrical signal. Traditional non-contact displacement sensors are resistive, inductive, capacitive, magnetic and optical type.

Don't need conduction rod and direct detection target displacement sensor as non-contact displacement sensor. Non-contact displacement sensors usually use inductor, or electromagnetic technology, laser, infrared, microwave or ultrasonic ranging. The need to establish and maintain position offset and tolerance of engineering applications, the displacement sensor is widely used. According to different requirements, the measuring range of displacement also vary widely, from the need to use a long wavelength microwave devices measure the displacement of the km to level short-wave microwave device measuring meters long displacement, the commonly used displacement sensor measurement millimeter level displacement, and micron level displacement is measured with laser interferometry, until the measured with X-ray diffraction interferometry and the nanometer level displacement.

Displacement sensor is often used in daily life, such as the monitor on the traffic lights and robots, precise control drive and drive system used to measure the drive or drive rod position of optical encoder. They played a great role in building the information society.