Dielectric Metasurfaces for Broadband Phase-Contrast Relief-Like Imaging

Abstract

The visualization of transparent specimens in traditional light microscopy is impeded by insufficient intrinsic contrast, prompting the development of advanced contrastenhancement methodologies to transmute minute phase discrepancies into detectable amplitude alterations. While existing methods excel in either phase-contrast imaging (contrast-enhanced image of whole objects) or relief-like imaging (deceptive threedimensional images), it would be of great significance to seamlessly integrate both capabilities in the same device. Here, we propose a novel metasurface-assisted half-side phase-contrast technique capable of simultaneous phase-contrast and relief-like imaging across the visible spectrum, which is realized by introducing a ±π/ 2 phase shift to a half-side diffracted wave emitted by the objects. Our method showcases successful application to diverse specimens, including a transparent silica disk and a frog egg cell. Our work substantiates high-quality microscopic imaging of various transparent specimens, which has profound implications in cellular biology, materials science, and medical diagnostics.