13-fold resolution gain through turbid layer via translated unknown speckle illumination.

Kaikai Guo,Jingang Zhong,Guoan Zheng,Zibang Zhang,Shaowei Jiang,Jun Liao,Yonina C Eldar

doi:10.1364/boe.9.000260

Abstract

Fluorescence imaging through a turbid layer holds great promise for various biophotonics applications. Conventional wavefront shaping techniques aim to create and scan a focus spot through the turbid layer. Finding the correct input wavefront without direct access to the target plane remains a critical challenge. In this paper, we explore a new strategy for imaging through turbid layer with a large field of view. In our setup, a fluorescence sample is sandwiched between two turbid layers. Instead of generating one focus spot via wavefront shaping, we use an unshaped beam to illuminate the turbid layer and generate an unknown speckle pattern at the target plane over a wide field of view. By tilting the input wavefront, we raster scan the unknown speckle pattern via the memory effect and capture the corresponding low-resolution fluorescence images through the turbid layer. Different from the wavefront-shaping-based single-spot scanning, the proposed approach employs many spots (i.e., speckles) in parallel for extending the field of view. Based on all captured images, we jointly recover the fluorescence object, the unknown optical transfer function of the turbid layer, the translated step size, and the unknown speckle pattern. Without direct access to the object plane or knowledge of the turbid layer, we demonstrate a 13-fold resolution gain through the turbid layer using the reported strategy. We also demonstrate the use of this technique to improve the resolution of a low numerical aperture objective lens allowing to obtain both large field of view and high resolution at the same time. The reported method provides insight for developing new fluorescence imaging platforms and may find applications in deep-tissue imaging.

Highlights

Imaging through turbid layer holds great promise for many biophotonics applications
This strategy is different from previous structured illumination (SI) demonstrations which uses multiple speckle patterns and allows us to achieve more than one order of magnitude resolution gain without direct access to the object plane
In summary, we report a new strategy for improving fluorescence imaging resolution through a turbid layer with a large field of view

Summary

Introduction

Imaging through turbid layer holds great promise for many biophotonics applications. Various approaches have been reported in recent years, including wavefront shaping techniques [1,2,3,4,5,6,7,8,9], measurement of the transmission matrix [10], object recovery from its autocorrelation [11, 12], accumulation of single-scattered waves [13], among others. By tilting the input wavefront, we raster scan the unknown speckle pattern via the memory effect and capture the corresponding low-resolution fluorescence images through the turbid layer (Visualization 1). Without direct access to the object plane or knowledge of the illumination pattern, we achieve one order of magnitude resolution enhancement using the reported strategy (Fig. 1(b)-1(c), will be discussed later). In this work we explore such super resolution by relying on the memory effect which allows to obtain many images from a single unknown speckle pattern This strategy is different from previous SI demonstrations which uses multiple speckle patterns and allows us to achieve more than one order of magnitude resolution gain without direct access to the object plane.

Modeling and simulation

Findings

Discussion