Precision non-contact displacement sensor based on the near-field characteristics of fiber specklegrams

•A low-cost method to perform precise non-contact displacement measurement by exploiting the near-field chrematistics of fiber specklegrams.•The fiber-optic sensor achieves a resolution and repeatability of 10 nm and a detection range of 3–4 μm at 100 Hz.•Advantages (1) low-cost, (2) compact device envelope, (3) high precision, and (4) insensitivity to sample/target materials.