Polarization Multi-Image Synthesis with Birefringent Metasurfaces

TL;DR

This paper presents a novel birefringent metasurface system that captures four coded measurements in a single shot, enabling flexible, multi-filter incoherent opto-electronic filtering with improved efficiency and adaptability.

Contribution

It introduces a new metasurface-based system for multi-filter imaging, along with a gradient descent design method and regularizer for customizing spatial filters from a single capture.

Findings

Successful simulation and prototype demonstrations.

Ability to realize a continuous family of spatial filters.

Filters with depth and wavelength variations.

Abstract

Optical metasurfaces composed of precisely engineered nanostructures have gained significant attention for their ability to manipulate light and implement distinct functionalities based on the properties of the incident field. Computational imaging systems have started harnessing this capability to produce sets of coded measurements that benefit certain tasks when paired with digital post-processing. Inspired by these works, we introduce a new system that uses a birefringent metasurface with a polarizer-mosaicked photosensor to capture four optically-coded measurements in a single exposure. We apply this system to the task of incoherent opto-electronic filtering, where digital spatial-filtering operations are replaced by simpler, per-pixel sums across the four polarization channels, independent of the spatial filter size. In contrast to previous work on incoherent opto-electronic filtering that can realize only one spatial filter, our approach can realize a continuous family of filters from a single capture, with filters being selected from the family by adjusting the post-capture digital summation weights. To find a metasurface that can realize a set of user-specified spatial filters, we introduce a form of gradient descent with a novel regularizer that encourages light efficiency and a high signal-to-noise ratio. We demonstrate several examples in simulation and with fabricated prototypes, including some with spatial filters that have prescribed variations with respect to depth and wavelength. Visit the Project Page at https://deanhazineh.github.io/publications/Multi_Image_Synthesis/MIS_Home.html