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

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.

Noninvasive time-lapse 3D subcellular analysis of embryo development for machine learning-enabled prediction of blastocyst formation

“…The former can be implemented by using a camera with high enough signal-to-noise ratio to detect lower light levels effectively. More complex modifications could address the latter, such as altering the illumination schemes 49 or applying spectral-multiplexing to optimize illuminations 50 . These adjustments aim to refine the balance between image quality and embryo safety, enhancing the practicality of using HT in sensitive developmental studies.…”

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“…Yet, this method enables RI imaging at a given depth, and thus axial scanning is required to generate a 3D RI tomogram. 32 Ge et al reported on a high-speed ODT method based on angle multiplexing and a deep-learning-based image reconstruction network. 33 However, this method involves network training with large paired data sets.…”

“…Single-shot RI slice imaging has been demonstrated based on the depth-resolved transfer function. Yet, this method enables RI imaging at a given depth, and thus axial scanning is required to generate a 3D RI tomogram . Ge et al reported on a high-speed ODT method based on angle multiplexing and a deep-learning-based image reconstruction network .…”