Ultracompact Achromatic Spiral Phase Contrast Imager on a CMOS Chip

Abstract

Spiral phase contrast (SPC) imaging, renowned for its label‐free imaging capabilities, has garnered great attention in microscopy, biomedical science, and material science. Despite the adoption of ultrathin metasurfaces as substitutes for conventional SPC optical components, the overall optical systems remain bulky and suffer from chromatic aberration owing to the light dispersion. Here, an ultracompact achromatic SPC imager (UASI) integrated onto a complementary metal‐oxide‐semiconductor chip is presented. The UASI combines vertically integrated refractive and diffractive optical elements, including a refractive microlens for high‐resolution imaging and a diffractive spiral microlens to compensate for chromatic aberration, thereby achieving achromatic SPC imaging. This UASI, fabricated by 3D direct laser writing, realizes edge‐enhanced imaging with high efficiency (≈60%) under broadband light illumination (450–660 nm). The demonstration paves the way for the utilization of hybrid micro‐optics in advanced imaging, providing an ultracompact achromatic solution for edge‐enhanced imaging, object recognition, biomedical, and material science applications.