Polarization-Multiplexed Metalens Enables Switchable and Compact Chromatic Confocal Sensing with Dual-Mode Precision Control.

Chromatic confocal measurement, as a non-contact, rapid, and high-precision optical technique, holds significant applications in industrial manufacturing, biomedical imaging, and ultraprecision metrology. However, conventional implementations relying on refractive lens assemblies suffer from inherent limitations in size, weight, and functional flexibility, limiting compatibility across diverse scenarios. Metalens, as a planar, ultrathin, and multifunctional optical element, exhibits inherent dispersion advantages. Here, conventional design paradigms are broken by leveraging a polarization-multiplexed metasurface to create the first chromatic confocal sensor with dynamically switchable measurement modes, achieving 10-fold miniaturization (Ø1 mm). The sensor not only offers significant advantages such as lightweight and integration, but also provides additional measurement modes, including high-accuracy and extended-range modes. Following the tests of system, measurement range of 400 µm and 1.57 mm, axial accuracy of ± 0.25 and ± 1.45 µm are achieved, under orthogonal polarized illumination within a 500-700 nm operating wavelength range, respectively. Further, to verify the performance of measurement system facing different measurement requirements, the three-dimensional (3D) topography of a concave spherical mirror and the thickness of transparent glass sheet are measured successfully. The novel chromatic confocal sensor demonstrates great potential for practical optical metrology and establishes a new design framework for adaptive multi-functional metrology systems.