Publications associées à Simulation of microoptics under inhomogeneous illumination: Sinusoidal Phase Grating under Gaussian Beam Illumination

Measuring electrical properties in semiconductor devices by pixelated STEM and off-axis electron holography (or convergent beams vs. plane waves)

We demonstrate the use of both pixelated differential phase contrast (DPC) scanning transmission electron microscopy (STEM) and off-axis electron holography (EH) for the measurement of electric fields and assess the advantages and limitations of each techn ...

Pergamon-Elsevier Science Ltd2024

An elementary treatment on the diffraction of crystalline structures

Gervais Chapuis

Although W. L. Bragg's law can be easily derived for beginners in the field of crystallography, its interpretation however seems to cause some difficulties which lies essentially in the relation between the concept of lattice planes and the unit cell const ...

2022

A Compressive Sensing Framework for EMI Source Localization Using a Metalens Structure: Localization Beyond the Diffraction Limit

Farhad Rachidi-Haeri, Marcos Rubinstein, Mohammad Azadifar, Hamidreza Karami

In this article, we propose a novel approach for the localization of electromagnetic interference (EMI) sources based on the concept of compressive sensing and metalenses. We show that using the spatial and frequency dispersion offered by the metalens, we ...

2022

Narrowband Optical Coupler Using Fano Interference in First Order Diffraction

Olivier Martin, Benjamin Gallinet, Fabian Michael Lütolf, Giorgio Quaranta

Light coupling in waveguides has been extensively investigated in a variety of contexts, from photonic integrated circuits to biosensing and near-eye displays for augmented reality. Here, narrowband diffraction is reported using a Fano interference effect ...

AMER CHEMICAL SOC2021

Structured light generation by refractive-diffractive micro optical array illuminators

Maryam Yousefi

Structured light generation having broad applications in different optical fields, is the topic of this thesis. Our structured light generation strategy is based on applying periodic microoptical elements at the refraction-diffraction limit, under a focuse ...

EPFL2021

Light pattern generation with hybrid refractive microoptics under Gaussian beam illumination

Toralf Scharf, Maryam Yousefi

The generation of wide-angle diffraction patterns can be done in different ways using either thin diffractive optical elements with small features sizes or arrays of microoptics with large optical paths that are thick diffractive optical elements. Our aim ...

2020

Diffraction artefacts from twins and stacking faults, and the mirage of hexagonal, polytypes or other superstructures

Cyril Cayron

Recently, a hexagonal phase has been reported in high carbon steels in several studies. Here, we show that the electron microscopy results used in these studies were erroneously interpreted. The extra-spots in the diffraction patterns and the odd contrasts ...

2020

Refinement for single-nanoparticle structure determination from low-quality single-shot coherent diffraction data

Christophe Nicolas, Christoph Bostedt

With the emergence of X-ray free-electron lasers, it is possible to investigate the structure of nanoscale samples by employing coherent diffractive imaging in the X-ray spectral regime. In this work, we developed a refinement method for structure reconstr ...

INT UNION CRYSTALLOGRAPHY2020

Imaging plasma formation in isolated nanoparticles with ultrafast resonant scattering

Daniela Rupp, Christoph Bostedt, Alessandro Colombo

We have recorded the diffraction patterns from individual xenon clusters irradiated with intense extreme ultraviolet pulses to investigate the influence of light-induced electronic changes on the scattering response. The clusters were irradiated with short ...

2020

Characterizing crystalline defects in single nanoparticles from angular correlations of single-shot diffracted X-rays

Giorgio Rossi, Christoph Bostedt, Alessandro Colombo

Characterizing and controlling the uniformity of nanoparticles is crucial for their application in science and technology because crystalline defects in the nanoparticles strongly affect their unique properties. Recently, ultra-short and ultra-bright X-ray ...

INT UNION CRYSTALLOGRAPHY2020

Near-field phase profile and far-field contrast modulation for micro-lens arrays at the refraction limit

Toralf Scharf, Maryam Yousefi, Daniel Necesal

We investigate the far-field pattern generation for a micro-lens array (MLA) illuminated under different conditions. Plane wave and Gaussian beam illumination are considered for an MLA with a small diameter of 27 microns and 30 microns period. At these dim ...

2020

Characterization of metal organic frameworks of interest for gas adsorption/separation applications

Mehrdad Asgari

Metal-Organic Frameworks (MOFs) are a class of porous materials that are applicable in many energy and environmentally relevant areas, due to their unique features including unprecedented internal surface areas and easy chemical tunability. Gas separation ...

EPFL2020

Terahertz surface modes and electron-phonon coupling on Bi2Se3(111)

Davide Campi

We present a combined experimental and theoretical study of the surface vibrational modes of the topological insulator Bi2Se3 with particular emphasis on the low-energy region below 10 meV that has been difficult to resolve experimentally. By applying inel ...

AMER PHYSICAL SOC2020

High-throughput and adaptive super-resolution fluorescence microscopy of organelles

Dora Mahecic

Fluorescence super-resolution microscopy has allowed unprecedented insight into the workings of biological systems below the diffraction limit of light. Over the past decade, it has overcome several challenges to deliver 3D, multi-color and faster imaging ...

EPFL2020

Time-lapse reconstruction of the fracture front from diffracted waves arrivals in laboratory hydraulic fracture experiments

Brice Tanguy Alphonse Lecampion, Thomas Emmanuel Blum, Dong Liu

4-D acoustic imaging via an array of 32 sources/32 receivers is used to monitor hydraulic fracture (HF) propagating in a 250 mm cubic specimen under a true-triaxial state of stress. We present a method based on the arrivals of diffracted waves to reconstru ...

2020

Far-Field Subwavelength Acoustic Imaging by Deep Learning

Romain Christophe Rémy Fleury, Bakhtiyar Orazbayev

Seeing and recognizing an object whose size is much smaller than the illumination wavelength is a challenging task for an observer placed in the far field, due to the diffraction limit. Recent advances in near- and far-field microscopy have offered several ...

American Physical Society2020

Design and Analysis of Binary Fan-out Gratings based on Step-Transition Perturbation Approach

Toralf Scharf, Dong Cheon Kim

Nowadays, diffractive optical elements are used for a variety of applications because of their high design flexibility, compact size, and mass productivity. At the same time, they require having high and complex optical functionalities such as a large numb ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Diffractive Optical Elements Investigation in the Phase Domain

Myun Sik Kim, Toralf Scharf, Michail Symeonidis, Dong Cheon Kim

In this work we demonstrate the advantages of investigating diffractive optical elements in the phase domain. In this regime we can detect features that are not restrained by the diffraction limit and relate them to the geometrical and optical properties o ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Transmission Microsphere-Assisted Dark-Field Microscopy

Stéphane Perrin, Giorgio Quaranta, Hongyu Li

Microsphere-assisted microscopy allows the limit of the diffraction of light to overcome while being non-invasive, full-field, label-free, and easy-to-implement. However, the observation of translucent samples remains difficult using a classical bright-fie ...

WILEY-V C H VERLAG GMBH2019

Deformation and degradation of superelastic NiTi under multiaxial loading

Helena Van Swygenhoven, Steven Van Petegem, Wei-Neng Hsu, Efthymios Polatidis, Nicola Casati

The degradation of the superelastic properties of a commercial NiTi alloy is studied during uniaxial, biaxial and load-path-change cycling performed in-situ with synchrotron X-ray diffraction. Careful examination of the diffraction pattern during uniaxial ...

2019