Aymeric Le Gratiet

Université de Rennes 1 | UR1 · Laboratoire FOTON - Fonctions Optiques pour les Technologies de l'information

A full Mueller polarimeter was implemented on a commercial laser-scanning microscope. The new polarimetric microscope is based on high-speed polarization modulation by spectral coding using a wavelength-swept laser as a source. Calibration as well as estimation of the measurement errors of the device are reported. The acquisition of Mueller images...

Diffuse reflectance spectroscopy (DRS) has proven to be a powerful, reliable, and non-invasive optical method for characterizing a specimen. Nevertheless, these methods are based on a rudimentary interpretation of the spectral response and can be irrelevant to understanding 3D structures. In this work, we proposed adding optical modalities into a c...

Understanding the virology of the coronavirus at the structural level has gained utmost importance to overcome the constant and long-term health complications induced by them. In this work, the light scattering properties of SARS-CoV-2 of size 140 nm were simulated by using discrete dipole approximation (DDA) for two incident wavelengths 200 nm and...

Many books on polarization give tables of Mueller matrices. The coherency matrix has been found useful for interpretation of the Mueller matrix. Here we give a table of Mueller matrices M, coherency matrices C, and coherency matrix factors F for different polarization components and systems. F is not given for some complicated nondeterministic case...

Depolarization has been found to be a useful contrast mechanism in biological and medical imaging. The Mueller matrix can be used to describe polarization effects of a depolarizing material. An historical review of relevant polarization algebra, measures of depolarization, and purity spaces is presented, and the connections with the eigenvalues of...

Polarized light scanning microscopy is a non-invasive and contrast-enhancing technique to investigate anisotropic specimens and chiral organizations. However, such arrangements suffer from insensitivity to confined blend of structures at sub-diffraction level. Here for the first time, we present that the pixel-by-pixel polarization modulation conve...

Measures of purity for partially polarized fields in three dimensions, and in particular, the separation into circularly and linearly polarized contributions, are reexamined, and a new degree of total linear polarization introduced. Explicit expressions for the characteristic decomposition in terms of coherency matrix elements are presented, includ...

Understanding the structural organization of chromatin is essential to comprehend the gene functions. The chromatin organization changes in the cell cycle, and it conforms to various compaction levels. We investigated a chromatin solenoid model with nucleosomes shaped as cylindrical units arranged in a helical array. The solenoid with spherical-sha...

Mueller Matrix Microscopy exploits the generation and the analysis of polarized light to create label-free contrast in biological images. However, when dealing with Optical Scanning Microscopy, it is required a fast generation of the polarization states in order to obtain a good Signal-to-Noise Ratio at the pixel-dwell time rate. In this work, we p...

Mueller matrix (MM) microscopy is an advanced imaging technique providing a full characterization of the optical polarization fingerprint of a sample. The Lu-Chipman (LC) decomposition, a method based on the modeling of elementary polarimetric arrangements and matrix inversions, is the gold standard to extract each polarimetric component separately...

Many of the most important resolution improvements in polarization-based techniques are based on the reduction of scattering effects. However, the determination of the coherency matrix elements from the experimental Mueller matrix can take advantage of scattering measurements to obtain additional information on the structural organization of a samp...

Second, using Stokes-Mueller formalism, we demonstrate the potentiality to characterize the polarimetric transformation of non-labeled small animals. As proof of principle, we have imaged particular biological structures of interest (collagen fibers and muscles). Then, we study the polarimetric transformation of zebrafish preserved at different emb...

Circular Intensity Differential Scattering (CIDS) is based on the analysis of the circular polarized light scattering and has been proven to be an interesting label-free microscopy technique sensitive to the chiral organization at the submicroscopic level. However, this approach averages the localized contrasts related to the sample polarimetric pr...

Optical scanning microscopy techniques based on the polarization control of the light have the capability of providing non invasive label-free contrast. By comparing the polarization states of the excitation light with its transformation after interaction with the sample, the full optical properties can be summarized in a single 4×4 Mueller matrix....

To overcome the optical diffraction limit, several super-resolution microscopy techniques have been demonstrated. Circular intensity differential scattering (CIDS) based on polarized light scattering is a powerful super-resolution and noninvasive microscopy technique to crumble the abbe optical resolution limit for studying and monitoring biologica...

Mueller-matrix microscopy has proved to be an important tool to extract the full optical properties of a sample, without labeling or a priori knowledge of the sample. It consists of studying the interaction between the polarized light and the medium, which can be summarized in a single 4x4 element Mueller-matrix. In this way, this method gives acce...

Many of the most important resolution improvements in optical microscopy techniques are based on the reduction of scattering effects. The main benefit of polarimetry‐based imaging to this end is the discrimination between scattering phenomena originating from complex systems and the experimental noise. The determination of the coherency matrix elem...

In this work, we exploited the dual-frequency, dual-polarization emission of a Zeeman laser acting as illumination stage of a multimodal optical scanning microscope to obtain polarization-resolved images of biological samples.

Circular Intensity Differential Scattering (CIDS) provides a differential measurement of the circular right and left polarized light and has been proven to be a gold standard label-free technique to study the molecular conformation of complex biopolymers, such as chromatin. In early works, it has been shown that the scattering component of the CIDS...

Calculation of the eigenvectors of two- and three-dimensional coherency matrices, and the four-dimensional coherency matrix associated with a Mueller matrix, is considered, especially for algebraic cases, in the light of recently published algorithms. The preferred approach is based on a combination of an evaluation of the charac- teristic polynomi...

Expansion microscopy is a novel preparation method enhancing the optical resolution by expanding uniformly the relative distance between fluorescence molecules on a sample placed inside a polymerized gel matrix. However, the fluorescence labeling protocols require a skillful preparation taking part to denature the molecular ordering and need high l...

Polarized light scattering based techniques are non-invasive and label-free approaches allowing the description of physical parameters, such as size and molecular orientation of any kind of sample. More particularly, Mueller matrix polarimetry is a 4x4 elements mathematical tool which quantitatively describes the properties of sample from the measu...

We have successfully developed a polarization-resolved Light Scattering Spectroscopic Microscope (pLSS) that allows us to investigate the angular scattering signature of biological cells under polarized light illumination. Light scattering imaging is a label-free technique sensitive to the size, shape, and orientation of biomolecules under observat...

Microscopy techniques based on the measurements of polarimetric contrasts as proved to be an important tool to extract additional information about the organization and orientation of any anisotropic sample. More particularly, it has been proven their efficiency for quantitative methods for materials science and biomedical diagnosis. Among these te...

The Sinclair and Kennaugh matrices are widely used in the remote sensing discipline for signals detected in the backward direction. The connections between the Jones matrix and the Sinclair matrix, and between the Mueller matrix and the Kennaugh matrix are explored. Different operations on the Jones matrix and their corresponding effects on the Mue...

Zebrafish are powerful animal models for understanding biological processes and the molecular mechanisms involved in different human diseases. Advanced optical techniques based on fluorescence microscopy have become the main imaging method to characterize the development of these organisms at the microscopic level. However, the need for fluorescenc...

An important approach to interpretation of the Mueller matrix is based on the eigenvalues of the coherency matrix, given by the roots of a quartic characteristic equation. For the case of backscattering, one eigenvalue is zero from reciprocity arguments, and the characteristic equation reduces to a cubic. These two approaches (quartic and cubic) to...

Mueller-matrix scanning microscopy is a label-free method allowing the acquisition of the full optical properties of a sample in fields as relevant as ophthalmology and biomedical diagnosis [1, 2]. The interaction between the polarized light and the sample can be summarized in a single 4x4 elements Mueller-matrix giving access to polarimetric param...

The sensitivity of ptychographically retrieved phase information to controlled variations in refractive index and sample thickness was explored. Additionally we discuss our approach to imaging isolated nuclei by correlating the quantitative phase information from ptychography with the circular dichroism signal from circular intensity differential s...

Scanning microscopy techniques based on the measurements of polarimetric contrasts as proved to be an important tool to investigate the full optical properties of a sample without using fluorescence label. It has demonstrated their efficiency for quantitative methods for ophthalmology and biomedical diagnosis [1, 2]. Among these techniques, Mueller...

Circular Dichroism (CD) resolved scanning microscopy has proven to be an interesting label-free technique to study chiral biological systems [1]. This technique is based on the measurement of the difference of intensity between the circular left and right polarization states after interaction with the sample. It was demonstrated in early works that...

The elements of the coherency matrix give the strength of the components of a Mueller matrix in the coherency basis. The Z-matrix (called the polarization-coupling matrix or state-generating matrix) represents a partial sum of the coherency expansion. For transmission through a deterministic medium, the coherency elements can be used directly as ge...

Circular dichroism imaging has proved a powerful and simple method for extracting information on chiral molecules without specific fluorescent labels. Numerous mathematical models show that outside the absorption band, the circular dichroism signal comes from the scattering interaction and brings additional information about the organization of bio...

LIQUITOPY®: A Liquid Tunable Microscope to Study Chromatin Organization in the Cell Nucleus - Volume 24 Supplement - Alberto Diaspro, Nicholas Anthony, Paolo Bianchini, Isotta Cainero, Melody Di Bona, Luca Lanzanò, Aymeric Le Gratiet, Riccardo Marongiu, Michele Oneto, Simone Pelicci, Luca Pesce

We show that the coherency matrix associated with a general depolarizing Mueller matrix can be factorized into the product of a matrix, the coherency matrix factor, and its conjugate transpose. The coherency matrix factor contains all the information in the Mueller matrix, and directly shows useful properties in an illustrative fashion. Propagation...

The possibility of integrating different light-matter interaction ways for producing images in optical microscopy is the starting point for the design and realization of a brand new optical microscope that has been named “liquid tunable microscope”. This represents a new paradigm in data collection and image formation with a potential high impact i...

Many books on polarization give tables of Mueller matrices. The coherency matrix has been found useful for interpretetion of the Mueller matrix. Here we give a table of Mueller matrices M, coherency matrices C, and coherency matrix factors F for different polarization components and systems. F is not given for some complicated nondeterministic case...

La polarimétrie de Mueller est une technique optique qui mesure la réponse polarimétrique complète d’un milieu sous la forme d’une seule matrice de Mueller afin de remonter à ses propriétés optiques comme le dichroïsme, la biréfringence et la dépolarisation. Le couplage avec la microscopie non-linéaire (SHG par exemple) permet d’avoir accès à des i...

A new setup was recently proposed to perform Mueller matrix polarimetry at 100 kHz using a swept laser source, high order retarders and a single channel photodetector. In this communication, we present the implementation of this setup on a laser scanning microscope to perform high speed scanning Mueller microscopy in transmission. Calibration of th...

Nous présentons un nouveau montage polarimétrique de Mueller basé sur le principe de codage spectral de la polarisation et utilisant une source laser à balayage rapide en longueur d’onde (swept source) à la cadence de 100 kHz. Le montage est proposé en réflexion et utilise donc un cube séparateur dont la réponse polarimétrique a été caractérisée. N...

RÉSUMÉ Nous présentons un nouveau montage polarimétrique de Mueller basé sur le principe de codage spectral de la polarisation et utilisant une source laser à balayage rapide en longueur d'onde (swept source) à la cadence de 100 kHz. Le montage est proposé en réflexion et utilise donc un cube séparateur dont la réponse polarimétrique a été caractér...

Le LSOL s’intéresse depuis quelques années à la polarimétrie de Mueller par codage spectral de la polarisation. Ce genre inédit de polarimètre permet de faire la mesure d’une matrice de Mueller en un temps record (≈ µs) grâce à l’utilisation de la longueur d’onde comme support de codage de la polarisation. Dans sa forme précédente, le polarimètre u...

A new setup is proposed to perform high-speed Mueller polarimetry by spectral coding of polarization in a reflection configuration. The system uses a swept laser source and a photodiode, which results in a simple optical setup that allows measurement of Mueller matrices at 100 kHz repetition rate. A special focus is made on the influence of the cub...

Le LSOL s’intéresse depuis quelques années à la polarimétrie de Mueller par codage spectral de la polarisation [1]. Ce genre inédit de polarimètre permet de faire la mesure d’une matrice de Mueller en un temps record (≈ µs) grâce à l’utilisation de la longueur d’onde comme support de codage de la polarisation. Dans sa forme précédente [1], le polar...