arXiv subjects

Herve Hugonnet

Publications and source records attributed to Herve Hugonnet.

At least 19 recordsLinked to original sources

arXiv2026

Programmable spatial coherence tomography: diffraction-limited three-dimensional reflection imaging under modulated monochromatic illumination

Depth sectioning in reflection microscopy has predominantly relied on temporal coherence gating. Here we show that volumetric reflection tomography at diffraction-limited resolution can be achieved under monochromatic illumination by engineering spatial, rather than temporal, coherence. In programmable spatial coherence tomography (PSCT), a sequence of pupil-coded illumination patterns with angular-spectrum diversity generates measurement redundancy enabling the system to calibrate itself, jointly retrieving aberrations, illumination profiles, and sample motion without guide stars or modal priors. We demonstrate label-free volumetric imaging of thick human tissues, organoids, frequency-resolved dynamic contrast, and high-resolution in vivo brain imaging through a cranial window. These results position PSCT as an alternative to temporal coherence based reflection imaging in complex biological systems.

physics.optics↗

arXiv2026

Quantitative three-dimensional absorption imaging in standard brightfield microscopes

Optical absorption is a primary, label-defining contrast across biology, pathology, and materials science, yet three-dimensional quantitative absorption imaging has remained largely inaccessible to the brightfield microscopes used in everyday practice. We introduce quantitative absorption tomography (QAT), which recovers volumetric distributions of the extinction coefficient by treating brightfield image formation as a linear inverse problem in logarithmic intensity space and inverting a three-dimensional absorption optical transfer function. Under weak-scattering conditions, QAT yields spectrally resolved, three-dimensional absorption maps from through-focus image stacks acquired on standard brightfield platforms, without interferometry, coherent illumination, or sample rotation. We use QAT to track melanin dynamics in living melanoma cells without exogenous labels, image pigment organization in intact Petunia hybrida petals in vivo, and reconstruct chromogenic contrast across large H&E-stained human tissue volumes. By establishing absorption as a directly measurable volumetric quantity within standard brightfield workflows, QAT positions chromogenic contrast as a quantitative axis alongside fluorescence- and refractive-index-based imaging.

physics.optics↗

arXiv2026

Video-rate holographic telepresence via single-shot, reference-free wavefront measurement

We present a reference-free holographic telepresence system that directly captures and replays complex optical wavefronts from a single intensity speckle measurement. Using a pre-characterized geometric phase diffuser, the incident field self-interferes to form a speckle pattern, from which the wavefront is recovered via a speckle-correlation scattering-matrix approach and refined using smoothed amplitude flow with Nesterov acceleration. The reconstructed phase is directly projected onto a spatial light modulator for holographic replay. We demonstrate volumetric refocusing, dynamic three-dimensional reconstruction, and sustained video-rate operation at approximately 28 frames per second with modest communication bandwidth. The results highlight measurement-driven wavefront acquisition as a practical pathway toward compact and physically faithful holographic telepresence.

physics.optics↗

arXiv2025

Incoherent dielectric tensor tomography for quantitative 3D measurement of biaxial anisotropy

Biaxial anisotropy, arising from distinct optical responses along three principal directions, underlies the complex structure of many crystalline, polymeric, and biological materials. However, existing techniques such as X-ray diffraction and electron microscopy require specialized facilities or destructive preparation and cannot provide full three-dimensional (3D) information. Here we introduce incoherent dielectric tensor tomography (iDTT), a non-interferometric optical imaging method that quantitatively reconstructs the 3D dielectric tensor under incoherent, polarization-diverse illumination. By combining polarization diversity and angular-spectrum modulation, iDTT achieves speckle-free and vibration-robust mapping of biaxial birefringence with submicron resolution. Simulations and experiments on uniaxial and biaxial samples validate its quantitative accuracy. Applied to mixed and polycrystalline materials, iDTT distinguishes crystal types by their birefringent properties and reveals 3D grain orientations and boundaries. This approach establishes iDTT as a practical and accessible tool for quantitative, label-free characterization of biaxial anisotropy in diverse materials.

physics.optics↗

arXiv2025

Pupil Phase Series: A Fast, Accurate, and Energy-Conserving Model for Forward and Inverse Light Scattering in Thick Biological Samples

We present the pupil phase series (PPS), a fast and accurate forward scattering algorithm for simulating and inverting multiple light scattering in large biological samples. PPS achieves high-angle scattering accuracy and energy conservation simultaneously by introducing a spatially varying phase modulation in the pupil plane. By expanding the scattering term into a Taylor series, PPS achieves high precision while maintaining computational efficiency. We integrate PPS into a quasi-Newton inverse solver to reconstruct the three-dimensional refractive index of a 180 um-thick human organoid. Compared to linear reconstruction, our method recovers subcellular features-such as nuclei and vesicular structures-deep within the sample volume. PPS offers a scalable and interpretable alternative to conventional solvers, paving the way for high-throughput, label-free imaging of optically thick biological tissues.

physics.optics↗

arXiv2025

Speckle-based X-ray microtomography via preconditioned Wirtinger flow

Quantitative phase imaging has been extensively studied in X-ray microtomography to improve the sensitivity and specificity of measurements, especially for low atomic number materials. However, obtaining quantitative phase images typically requires additional measurements or assumptions, which significantly limits the practical applicability. Here, we present preconditioned Wirtinger flow (PWF): an assumption-free, single-shot quantitative X-ray phase imaging method. Accurate phase retrieval is demonstrated using a specialized gradient-based algorithm with an accurate physical model. Partial coherence of the source is taken into account, extending the potential applications to bench-top sources. Improved accuracy and spatial resolution over conventional speckle tracking methods are experimentally demonstrated. The various samples are explored to demonstrate the robustness and versatility of PWF.

physics.optics↗

arXiv2025

Generalized reciprocal diffractive imaging for stand-alone, reference-free, fast-measurable quantitative phase microscopy

Optical microscopy has been employed to derive salient characteristics of an object in various fields, including cell biology, flow cytometry, biopsy, and neuroscience. In particular, measuring the phase of light scattered from an object aroused great interest by allowing retrieving quantitative parameters such as refractive index, an intrinsic property of a material. Reciprocal diffractive imaging (RDI) has succeeded in recovering the light field scattered from diffusive objects without special restrictions on illumination and sample support from a single-shot intensity in the reference-free regime. However, RDI is limited to imaging samples in the diffusive regime, making application to biological samples difficult. Here, we extend RDI to biological applications by spatially filtering the transmitted fields in the pupil plane. The proposed method is demonstrated by imaging the objects with known structures and various biological samples, showing its capability as a stand-alone optical microscope. We believe that the presented advance could be at the forefront of quantitative phase imaging due to the unique advantages the technique possesses.

physics.optics↗

arXiv2024

Digital cytometry: extraction of forward and side scattering signals from holotomography

Flow cytometry is a cornerstone technique in medical and biological research, providing crucial information about cell size and granularity through forward scatter (FSC) and side scatter (SSC) signals. Despite its widespread use, the precise relationship between these scatter signals and corresponding microscopic images remains underexplored. Here, we investigate this intrinsic relationship by utilizing scattering theory and holotomography, a three-dimensional quantitative phase imaging (QPI) technique. We demonstrate the extraction of FSC and SSC signals from individual, unlabeled cells by analyzing their three-dimensional refractive index distributions obtained through holotomography. Additionally, we introduce a method for digitally windowing SSC signals to facilitate effective segmentation and morphology-based cell type classification. Our approach bridges the gap between flow cytometry and microscopic imaging, offering a new perspective on analyzing cellular characteristics with high accuracy and without the need for labeling.

physics.optics↗

arXiv2024

Rytov Approximation of Vectorial Waves by Modifying Scattering Matrixes: Precise Reconstruction of Dielectric Tensor Tomography

Analyzing 3D anisotropic materials presents significant challenges, especially when assessing 3D orientations, material distributions, and anisotropies through scattered light, due to the inherently vectorial nature of light-matter interactions. In this study, we formulate a scattering theory based on the Rytov approximation, commonly employed in scalar wave tomography, tailored to accommodate vector waves by modifying the scattering matrix. Using this formulation, we investigate the intricate 3D structure of liquid crystals with multiple topological defects exploiting dielectric tensor tomography. By leveraging dielectric tensor tomography, we successfully visualize these topological defects in three dimensions, a task that conventional 2D imaging techniques fail to achieve.

physics.optics↗

arXiv2024

High-precision and low-noise dielectric tensor tomography using a micro-electromechanical system mirror

Dielectric tensor tomography is an imaging technique for mapping three-dimensional distributions of dielectric properties in transparent materials. This work introduces an enhanced illumination strategy employing a micro-electromechanical system mirror to achieve high precision and reduced noise in imaging. This illumination approach allows for precise manipulation of light, significantly improving the accuracy of angle control and minimizing diffraction noise compared to traditional beam steering approaches. Our experiments have successfully reconstructed the dielectric properties of liquid crystal droplets, which are known for their anisotropic structures, while demonstrating a notable reduction in background noise of the imag-es. Additionally, the technique has been applied to more complex samples, revealing its capability to achieve a high signal-to-noise ratio. This development represents a significant step forward in the field of birefringence imaging, offering a powerful tool for detailed study of materials with anisotropic properties.

physics.optics↗

arXiv2023

Improving specificity and axial spatial resolution of refractive index imaging by exploiting uncorrelated subcellular dynamics

Holotomography, a three-dimensional quantitative phase imaging technique, presents an innovative, non-invasive approach to studying biological samples by exploiting the refractive index as an intrinsic imaging contrast. Despite offering label-free quantitative imaging capabilities, its potential in cell biology research has been stifled due to limitations in molecular specificity and axial resolution. Here, we propose and experimentally validate a solution to overcome these constraints by capitalizing on the intrinsic dynamic movements of subcellular organelles and biological molecules within living cells. Our findings elucidate that leveraging such sample motions enhances axial resolution. Furthermore, we demonstrate that the extraction of uncorrelated dynamic signals from refractive index distributions unveils a trove of previously unexplored dynamic imaging data. This enriched dataset paves the way for fresh insights into cellular morphologic dynamics and the metabolic shifts occurring in response to external stimuli. This promising development could broaden the utility of holotomography in cell biology.

physics.optics↗

arXiv2023

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

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.

physics.optics↗

arXiv2022

Dielectric-tensor reconstruction of highly scattering birefringent samples

Many important microscopy samples, such as liquid crystals, biological tissue, or starches, are birefringent in nature. They scatter light differently depending on the light polarization and molecular orientations. The complete characterization of a birefringent sample is a challenging task because its 3 x 3 dielectric tensor must be reconstructed at every three-dimensional position. Moreover, obtaining a birefringent tomogram is more arduous for thick samples, where multiple light scattering should also be considered. In this study, we developed a new dielectric tensor tomography algorithm that enables full characterization of highly scattering birefringent samples by solving the vectoral inverse scattering problem considering multiple light scattering. We proposed a discrete image-processing theory to compute the error backpropagation of vectorially diffracting light. Finally, our theory was experimentally demonstrated using both synthetic and biologically birefringent samples.

physics.optics↗

arXiv2022

Regularization of dielectric tensor tomography using total variation

Dielectric tensor tomography reconstructs the three-dimensional dielectric tensors of microscopic objects and provides information about the crystalline structure orientations and principal refractive indices. Because dielectric tensor tomography is based on transmission measurement, it suffers from the missing cone problem, which causes poor axial resolution, underestimation of the refractive index, and halo artifacts. In this study, we present the generalization of total variation regularization to three-dimensional tensor distributions. In particular, demonstrate the reduction of artifacts when applied to dielectric tensor tomography.

physics.optics↗

arXiv2022

Spatially multiplexed dielectric tensor tomography

Dielectric tensor tomography (DTT) enables the reconstruction of three-dimensional (3D) dielectric tensors, which provides a physical measure of 3D optical anisotropy. Herein, we present a cost-effective and robust method for DTT measurement using a multiplexing approach. By exploiting two orthogonally polarized reference beams with different angles in an off-axis interferometer, two polarization-sensitive interferograms were overlapped and recorded using a single camera. Then, the two multiplexed interferograms were separated in the Fourier domain, enabling the reconstruction of polarization-sensitive fields. Finally, by measuring the polarization-sensitive fields for various illumination angles, 3D dielectric tensor tomograms were reconstructed. The proposed method was experimentally demonstrated by reconstructing the 3D dielectric tensors of various liquid crystal particles with radial and bipolar orientational configurations.

physics.optics↗

arXiv2022

Quantitative phase imaging via the holomorphic property of complex optical fields

An optical field is described by the amplitude and phase, and thus has a complex representation described in the complex plane. However, because the only thing we can measure is the amplitude of the complex field on the real axis, it is difficult to identify how the complex field behaves throughout the complex plane. In this study, we interpreted quantitative phase imaging methods via the Hilbert transform in terms of analytic continuation, manifesting the behavior in the whole complex plane. Using Rouche's theorem, we proved the imaging conditions imposed by Kramers-Kronig holographic imaging. The deviation from the Kramers-Kronig holography conditions was examined using computational images and experimental data. We believe that this study provides a clue for holographic imaging using the holomorphic characteristics of a complex optical field.

physics.optics↗

arXiv2022

Quantitative phase and refractive index imaging of 3D objects via optical transfer function reshaping

Deconvolution phase microscopy enables high-contrast visualization of transparent samples through reconstructions of their transmitted phases or refractive indexes. Herein, we propose a method to extend 2D deconvolution phase microscopy to thick 3D samples. The refractive index distribution of a sample can be obtained at a specific axial plane by measuring only four intensity images obtained under optimized illumination patterns. Also, the optical phase delay of a sample can be measured using different illumination patterns.

physics.optics↗

arXiv2021

Single-shot wide-field topography measurement using spectrally multiplexed reflection intensity holography via space-domain Kramers-Kronig relations

Surface topology measurements of micro- or nanostructures is essential for both scientific and industrial applications. However, high-throughput measurements remain challenging in surface metrology. We present a single-shot full-field surface topography measurement using Kramers-Kronig holographic imaging and spectral multiplexing. Three different intensity images at different incident angles were simultaneously measured with three different colors, from which a quantitative phase image was retrieved using spatial Kramers-Kronig relations. A high-resolution topographic image of the sample was then reconstructed using synthetic aperture holography. Various patterned structures at the nanometer scale were measured and cross-validated using atomic force microscopy.

physics.optics↗