All-in-focus large-FOV GRIN lens imaging by multi-focus image fusion

Abstract

Gradient refractive index (GRIN) lenses are useful for miniaturized and in-vivo imaging. However, the intrinsic field-dependent aberrations of these lenses can deteriorate imaging resolution and limit the effective field of view. To address these aberrations, adaptive optics (AO) has been applied which inevitably requires the incorporation of additional hardware. Here we focus on field curvature aberration and propose a computational correction scheme which fuses a z-stack of images into a single in-focus image over the entire field of view (FOV), with no AO required. We validate our method by all-in-focus wide-field imaging of a printed letter sample and fluorescently labeled mouse brain slices. The method can also provide what we believe to be a new and valuable option for imaging enhancement in the scanning-modality use of GRIN lens microscopy.