1,371 research outputs found
Imaging Gold Nanoparticles in Living Cells Environments using Heterodyne Digital Holographic Microscopy
This paper describes an imaging microscopic technique based on heterodyne
digital holography where subwavelength-sized gold colloids can be imaged in
cell environment. Surface cellular receptors of 3T3 mouse fibroblasts are
labeled with 40 nm gold nanoparticles, and the biological specimen is imaged in
a total internal reflection configuration with holographic microscopy. Due to a
higher scattering efficiency of the gold nanoparticles versus that of cellular
structures, accurate localization of a gold marker is obtained within a 3D
mapping of the entire sample's scattered field, with a lateral precision of 5
nm and 100 nm in the x,y and in the z directions respectively, demonstrating
the ability of holographic microscopy to locate nanoparticles in living cells
environments
Single-shot experimental-numerical twin-image removal in lensless digital holographic microscopy
Lensless digital holographic microscopy (LDHM) offers very large
field-of-view label-free imaging crucial, e.g., in high-throughput particle
tracking and biomedical examination of cells and tissues. Compact layouts
promote point-of-case and out-of-laboratory applications. The LDHM, based on
the Gabor in-line holographic principle, is inherently spoiled by the
twin-image effect, which complicates the quantitative analysis of reconstructed
phase and amplitude maps. Popular family of solutions consists of numerical
methods, which tend to minimize twin-image upon iterative process based on data
redundancy. Additional hologram recordings are needed, and final results
heavily depend on the algorithmic parameters, however. In this contribution we
present a novel single-shot experimental-numerical twin-image removal technique
for LDHM. It leverages two-source off-axis hologram recording deploying simple
fiber splitter. Additionally, we introduce a novel phase retrieval numerical
algorithm specifically tailored to the acquired holograms, that provides
twin-image-free reconstruction without compromising the resolution. We
quantitatively and qualitatively verify proposed method employing phase test
target and cheek cells biosample. The results demonstrate that the proposed
technique enables low-cost, out-of-laboratory LDHM imaging with enhanced
precision, achieved through the elimination of twin-image errors. This
advancement opens new avenues for more accurate technical and biomedical
imaging applications using LDHM, particularly in scenarios where cost-effective
and portable imaging solutions are desired
Holographic Digital Fourier Microscopy for Selective Imaging of Biological Tissue
This paper presents an application of digital Fourier holography for
selective imaging of scatterers with different sizes in turbid media such as
biological tissues. A combination of Fourier holography and high-resolution
digital recording, digital Fourier microscopy (DFM) permits crucial flexibility
in applying filtering to highlight scatterers of interest in the tissue. The
high-resolution digital hologram is a result of the collation of Fourier
holographic frames to form a large-size composite hologram. It is expected that
DFM has an improved signal-to-noise ratio as compared to conventional direct
digital imaging, e.g. phase microscopy, as applied to imaging of small-size
objects. The demonstration of the Fourier filtering capacity of DFM using a
biological phantom represents the main focus of this paper.Comment: 24 pages, 5 figure
Improvements in Digital Holographic Microscopy
The Ph.D. dissertation consists of developing a series of innovative computational methods for improving digital holographic microscopy (DHM). DHM systems are widely used in quantitative phase imaging for studying micrometer-size biological and non-biological samples. As any imaging technique, DHM systems have limitations that reduce their applicability. Current limitations in DHM systems are: i) the number of holograms (more than three holograms) required in slightly off-axis DHM systems to reconstruct the object phase information without applying complex computational algorithms; ii) the lack of an automatic and robust computation algorithm to compensate for the interference angle and reconstruct the object phase information without phase distortions in off-axis DHM systems operating in telecentric and image plane conditions; iii) the necessity of an automatic computational algorithm to simultaneously compensate for the interference angle and numerically focus out-of-focus holograms on reconstructing the object phase information without phase distortions in off-axis DHM systems operating in telecentric regime; iv) the deficiency of reconstructing phase images without phase distortions at video-rate speed in off-axis DHM operating in telecentric regime, and image plane conditions; v) the lack of an open-source library for any DHM optical configuration; and, finally, vi) the tradeoff between speckle contrast and spatial resolution existing in current computational strategies to reduce the speckle contrast. This Ph.D. dissertation is motivated to overcome or at least reduce the six limitations mentioned above. Each chapter of this dissertation presents and discusses a novel computational method from the theoretical and experimental point of view to address each of these limitations
Roadmap on digital holography [Invited]
This Roadmap article on digital holography provides an overview of a vast array of research activities in the field of digital holography. The paper consists of a series of 25 sections from the prominent experts in digital holography presenting various aspects of the field on sensing, 3D imaging and displays, virtual and augmented reality, microscopy, cell identification, tomography, label-free live cell imaging, and other applications. Each section represents the vision of its author to describe the significant progress, potential impact, important developments, and challenging issues in the field of digital holography
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