Dielectric\nMetasurfaces for Broadband Phase-Contrast\nRelief-Like Imaging

The visualization of transparent specimens in traditional\nlight\nmicroscopy is impeded by insufficient intrinsic contrast, prompting\nthe development of advanced contrast-enhancement methodologies to\ntransmute minute phase discrepancies into detectable amplitude alterations.\nWhile existing methods excel in either phase-contrast imaging (contrast-enhanced\nimage of whole objects) or relief-like imaging (deceptive three-dimensional\nimages), it would be of great significance to seamlessly integrate\nboth capabilities in the same device. Here, we propose a novel metasurface-assisted\nhalf-side phase-contrast technique capable of simultaneous phase-contrast\nand relief-like imaging across the visible spectrum, which is realized\nby introducing a ±π/2 phase shift to a half-side diffracted\nwave emitted by the objects. Our method showcases successful application\nto diverse specimens, including a transparent silica disk and a frog\negg cell. Our work substantiates high-quality microscopic imaging\nof various transparent specimens, which has profound implications\nin cellular biology, materials science, and medical diagnostics.