Meta-Dispersive 3D Chromatic Confocal Measurement

3D reconstruction can perceive the detailed structures of real-world objects. Integrating metasurfaces with stereo vision or structured-light projection enables compact and efficient 3D reconstruction systems, beneficial for next-generation sensing, augmented reality, and biomedical applications. Nevertheless, the limitations inherent in these visual measurement methods pose a significant challenge to achieving higher resolution. Here, a dispersive metalens (DML) combined with the chromatic confocal method is proposed to achieve high-precision 3D measurement. With appropriate engineered dispersion, the linearity of the dispersion is well maintained, alongside diffraction-limited focusing performance. As a proof-of-concept, experiments on both longitudinal and transversal measurements are conducted. Following the calibration of the DML, axial accuracy of ±4 µm and a subwavelength axial resolution of 0.325 µm is achieved. The successful reconstruction of a fabricated 3D USAF-1951 resolution test chart further corroborates the 3D measurement capability, demonstrating a lateral resolution exceeding 4.38 µm. It is envisioned that the proposed method will pave the way for future applications in areas such as microstructure characterization, industrial inspection, and on-chip 3D optical metrology.