Ultrasensitive Vector Displacement Measurement Based on Pancharatnam‐Berry Phase Optical Element

Abstract Precise transverse displacement metrology is essential for super‐resolution microscopy, precision engineering, and semiconductor manufacturing. Conventional methods encounter challenges related to miniaturization, complexity, and sensitivity to transverse motion. Metasurface‐based methods achieve nanometric resolution but are hindered by fabrication complexity, limited dynamic range, and ambiguity in absolute displacement measurement. An ultrasensitive vector displacement sensor utilizing liquid crystal optical elements (LCOE) under vector beam illumination is presented. By mapping the transverse displacement to the polarization change of a radial vector beam, the displacement length can be directly inferred using Malus' law, and the displacement direction can be easily determined from the rotation of the vector beam speckle. Remarkably, uncertainties of 47 and 55 pm are achieved over centimeter‐scale ranges, with step sizes of 10 and 5 nm, respectively. This method combines nanometric resolution, an extended dynamic range, and compactness, providing innovative metrological principles for next‐generation precision measurement applications. The integration of LCOEs and vector beams enables absolute displacement measurement without the need for complex nanofabrication, overcoming critical limitations of current technologies.