Engineered Metalenses for Aberration Correction in Light Sheet Fluorescence Microscopy

Abstract

Light sheet fluorescence microscopy (LSFM) uses a thin sheet of light to selectively illuminate fluorophores within a focal volume. This type of microscopy is advantageous as it reduces photobleaching and phototoxicity to a fraction of a sample while maintaining high imaging speed. The spatial configuration of a LSFM system however can limit its compatibility with commonly used biological sample holders such as multi-well plates. An open-top LSFM configuration permits the utilization of these widely used biological sample holders. The detriment to this configuration is that it introduces system-induced aberrations from the tilt of the sample holder in respect to the optical axis. These aberrations distort the image and result in a lower imaging resolution. This project explores the use of metasurfaces, a novel technology with the unique ability to manipulate electromagnetic waves in microwave and optical frequencies, to correct for these aberrations. Through the geometric properties of nanostructures, metasurfaces have the ability to block, absorb, concentrate, disperse, and guide wavefronts. Metalenses are a subset of metasurfaces with a specific phase profile used in imaging and focusing applications. The project first creates a simulation of the aberrated phase profile generated by the open-top LSFM configuration. It then uses the simulation to design a phase profile to compensate for the aberration. The corrected phase profile is transformed into a meta-atom layout which will be fabricated onto a metalens. This thesis specifically focuses on the design and verification of a metasurface to correct for aberrations produced by a 35 degree tilt of the sample holder in respect to the optical axis. Fabrication and testing of the metasurface are left to future work. The goal is for the customized metalens to reduce the detrimental effects of a system-induced aberration and therefore improve the resolution of the imaging system. With the correction of these aberrations, researchers can take advantage of LSFM benefits as well as widely-used biological sample holders for high-throughput imaging without a diminishment in resolution.