Single-shot refractive index slice imaging using spectrally multiplexed optical transfer function reshaping

TL;DR

This paper introduces a novel single-shot method for imaging the refractive index of biological samples using spectral multiplexing and optical transfer function engineering, enabling fast, noninvasive, and high-resolution RI measurements.

Contribution

It presents a new single-shot RI imaging technique that uses spectral multiplexing and transfer function reshaping to visualize in-focus slices without bulky setups.

Findings

Successfully measured RI of microspheres with validation

Achieved subcellular resolution in biological cell imaging

Demonstrated rapid imaging of dynamic biological samples

Abstract

The refractive index (RI) of cells and tissues is crucial in pathophysiology as a noninvasive and quantitative imaging contrast. Although its measurements have been demonstrated using three-dimensional quantitative phase imaging methods, these methods often require bulky interferometric setups or multiple measurements, which limits the measurement sensitivity and speed. Here, we present a single-shot RI imaging method that visualizes the RI of the in-focus region of a sample. By exploiting spectral multiplexing and optical transfer function engineering, three color-coded intensity images of a sample with three optimized illuminations were simultaneously obtained in a single-shot measurement. The measured intensity images were then deconvoluted to obtain the RI image of the in-focus slice of the sample. As a proof of concept, a setup was built using Fresnel lenses and a liquid-crystal display. For validation purposes, we measured microspheres of known RI and cross-validated the results with simulated results. Various static and highly dynamic biological cells were imaged to demonstrate that the proposed method can conduct single-shot RI slice imaging of biological samples with subcellular resolution.