Resolution enhancement for light field microscopic 3D imaging based on polarization and data fusion

Light field microscopy (LFM) is an emerging three-dimensional (3D) imaging technology that simultaneously captures both spatial and angular information of the incident light by placing a micro lens array (MLA) in front of an imaging sensor, enabling computational reconstruction of the full 3D volume of a specimen via a single camera frame or single shot imaging. Unlike other 3D imaging techniques that acquire spatial information sequentially or through scanning, LFM four-dimensional (4D) imaging scheme effectively frees volume acquisition time from spatial scales and easy to miniaturize, thus making LFM a highly scalable tool in diverse applications. However, its broad application has slowed down due to the low resolution of the limited angular and spatial information in one snapshot of captured image, the inhomogeneous resolution of reconstructed depth images, and the lack of lateral shift invariance, which greatly degrades the spatial resolution, causing grid-like artifacts and great computational complexity. The introduction of Fourier light field microscopy (FLFM) provides a promising path to improve the current LFM techniques and achieve high-quality imaging and rapid light field reconstruction. However, the inherent trade-off between the angular and spatial resolution is still not fundamentally resolved without the introduction of additional information. Polarization, another dimension of light field information, has been shown to integrate well with other 3D imaging techniques to obtain finer 3D reconstructions results. Unfortunately, this aspect has seldom received attention and is ignored in LFM. This paper presents a resolution enhancement scheme for Fourier light field microscopy system that utilizes polarization norms and light field point cloud data fusion to generate improved imaging resolution and 3D reconstruction accuracy. Different from conventional FLFM, this approach actively introduces additional surface polarization information of the sample into the reconstruction of 3D volume information. A universal polarization-integrated FLFM configuration is designed and built up, allowing polarization and light field data to be acquired simultaneously using the same set of optical paths. A mathematical model is derived to describe the mapping and fusion of the polarization norms and light field point cloud data. Simulation studies show that the resolution and accuracy of the 3D reconstruction of the proposed FLFM imaging system are significantly improved after incorporating the polarization information, confirming the validity of the proposed methods. Finally, the implications of this approach for FLM are discussed, providing guidance for future experiments and applications. The resolution enhancement approach based on polarization and data fusion provides a feasible solution to the contradiction between lateral resolution and vertical resolution, and further improve the resolution of the FLFM imaging system.