Metasurfaces for Infrared Multimodal Microscopy: Phase Contrast and Bright Field

Different imaging modalities are used to visualize the diverse information carried in an optical field. Two prominent non-computational modalities include bright field and phase contrast microscopy that can create contrast in an image related to the amplitude and phase features of a sample, respectively. Often, the size and cost of the equipment typically required for these applications, such as bulky microscopes, can limit their availability to well-equipped laboratories. Furthermore, capturing both of the phase contrast and bright field images on the same camera in a microscope typically requires interchanging optical components. Metasurfaces are ultra-thin nanostructures that can merge both of these operations into a single miniaturized device in the push toward shrinking the size of imaging systems. Here, a silicon-based metasurface that supports a Mie resonance is demonstrated to perform non-computational, near-infrared phase contrast and bright field multimodal microscopy that can be tuned by changing the polarization of the illumination. We performed experiments using optical fields with phase variations synthesized by a spatial light modulator and introduced by propagation through semi-transparent samples, including C. elegans, unstained human prostate cancer cells, and breast tissue. The results demonstrate the potential of metasurfaces to be used in miniaturized optical systems for label-free point-of-care testing beyond the laboratory.