Metasurface-based super-resolution image scanning microscopy

Image scanning microscopy (ISM) enhances optical resolution by applying pixel reassignment. A large number of evenly generated focal points is essential for this method, as it involves scanning a multifocal array. Historically, multifocal arrays have been produced using electronically controlled optical modulators such as digital micromirror devices (DMDs) or microlens arrays. However, electronic modulators can be cost-inefficient and require intricate alignment, while microlens arrays often demand a lengthy optical path for demagnification and have limited numerical aperture, resulting in bulky systems that are challenging to align and maintain. In this work, we introduce a novel multifocal metalens design capable of providing a dense and uniform distribution of focal points to enable ISM. Metalenses, constructed from regularly arranged nanostructures, offer ultrathin profiles and versatile optical modulation functions. As a proof of concept, we developed an ISM system using our multifocal metalens and successfully captured super-resolution images of neurons in brain organoids. We anticipate that our method will guide the creation of advanced, streamlined optical microscopes based on metalens technology.