This paper presents a microscopic imaging technique that uses variable-angle illumination to recover the complex polarimetric properties of a specimen at high resolution and over a large field-of-view. The approach extends Fourier ptychography, which is a synthetic aperture-based imaging approach to improve resolution with phaseless measurements, to additionally account for the vectorial nature of light. After images are acquired using a standard microscope outfitted with an LED illumination array and two polarizers, our vectorial Fourier ptychography (vFP) algorithm solves for the complex 2x2 Jones matrix of the anisotropic specimen of interest at each resolved spatial location. We introduce a new sequential Gauss-Newton-based solver that additionally jointly estimates and removes polarization-dependent imaging system aberrations. We demonstrate effective vFP performance by generating large-area (29 mm), high-resolution (1.24 m full-pitch) reconstructions of sample absorption, phase, orientation, diattenuation, and retardance for a variety of calibration samples and biological specimens.
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http://dx.doi.org/10.1364/BOE.448804 | DOI Listing |
Histochem Cell Biol
December 2024
School of Mechanical, Medical & Process Engineering, Queensland University of Technology, 60 Musk Ave/Cnr. Blamey St, Kelvin Grove, Brisbane, QLD, 4059, Australia.
Understanding the osteochondral junction, where non-mineralised cartilage and mineralised bone converge, is crucial for joint health. Current sample preparation techniques are insufficient for detailed spatial hyperspectral imaging analysis. Using the enhanced Kawamoto method, we used the super cryo embedding medium's temperature-dependent properties to transfer high-quality tissue samples onto slides for spatial imaging analysis.
View Article and Find Full Text PDFDeep neural network (DNN) models, particularly convolutional neural networks (CNNs), have demonstrated remarkable performance in biomedical image classification due to their ability to automatically learn features from large datasets. One common challenge in the preparation of large, microscopic datasets for DNN tasks is sample defocusing, potentially impairing the model performance. To handle defocusing, computational imaging, or specifically quantitative phase imaging (QPI), performs digital refocusing by using both the phase and the amplitude of the complex optical field.
View Article and Find Full Text PDFAdv Opt Mater
May 2024
Department of Biomedical Engineering, University of Connecticut, Storrs, USA.
Small Methods
October 2024
Optical Bioimaging Laboratory, Department of Biomedical Engineering, College of Design and Engineering, National University of Singapore, Singapore, 117576, Singapore.
Fourier ptychography (FP) is a high resolution wide-field imaging method based on the extended aperture in the Fourier space, which is synthesized from raw images with varying illumination angles. If FP is extended to coherent nonlinear optical imaging, the resolution could be further improved due to the increase of the cutoff frequency of the synthesized coherent optical transfer function (C-OTF) with respect to the order of nonlinear optical processes. However, there is a fundamental conflict between wide-field FP and nonlinear optical imaging, whereby the nonlinear optical imaging typically requires a focused excitation laser beam with high power density.
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