3D imaging using scanning diffractometry

Morteza J Siavashani,Mohammad Taghi Tavassoly,Iman Naghedi,Ali-Reza Moradi,Vahid Abbasian,Ehsan A Akhlaghi,Mohammad A Charsooghi

doi:10.1038/s41598-020-79939-y

Abstract

Imaging of cells is a challenging problem as they do not appreciably change the intensity of the illuminating light. Interferometry-based methods to do this task suffer from high sensitivity to environmental vibrations. We introduce scanning diffractometry as a simple non-contact and vibration-immune methodology for quantitative phase imaging. Fresnel diffractometry by a phase step has led to several applications such as high-precision measurements of displacement. Additional scanning may lead to 3D imaging straightforwardly. We apply the technique to acquire 3D images of holographic grating, red blood cell, neuron, and sperm cell. Either visibility of the diffraction fringes or the positions of extrema may be used for phase change detection. The theoretical analysis through the Fresnel diffraction from one-dimensional phase step is presented and the experimental results are validated with digital holographic microscopy. The presented technique can be suggested to serve as a robust device for 3D phase imaging and biomedical measurements.

Highlights

Imaging of cells is a challenging problem as they do not appreciably change the intensity of the illuminating light
For the U87 cell (Fig. 5b), we obtained body sizes as W = 84.0 μm, H = 88.5 μm, and axon length as TM = 67.05 μm, which are in agreement with the sizes provided by the American Type Culture Collection (ATCC)[54]
We introduce an interference-free and highly sensitive quantitative phase imaging (QPI) method based on Fresnel diffraction from a phase step

Summary

Introduction

Imaging of cells is a challenging problem as they do not appreciably change the intensity of the illuminating light. Optical imaging techniques possess several benefits; they can detect functional and structural changes with high sensitivity, they are non-invasive and real-time, and they can be set up portable with low equipment cost. For detecting the optical phase changes of the sample methods such as Zernike phase contrast microscopy[16] and differential interference contrast microscopy[4] are utilized. Among the techniques to obtain a quantitative assessment of the optical phase changes, 3D imaging, DHM has been emphasized and developed more than others[24,25]. Due to the overall instability of the optical system, the remained noises still affect the quality of the reconstructed images Most of these arrangements work efficiently only if the sample under study contains large sparse domains[35]. This, in turn, leads to the requirement of fine adjustment of the optical system to achieve high quality holography fringes

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Conclusion