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Concept

Nombre de Fresnel

Publications associées (17)

A Low-Temperature Annealing Method for Alloy Nanostructures and Metasurfaces: Unlocking a Novel Degree of Freedom

Olivier Martin, Christian Santschi, Hsiang-Chu Wang, Jeonghyeon Kim, Debdatta Ray

The material and exact shape of a nanostructure determine its optical response, which is especially strong for plasmonic metals. Unfortunately, only a few plasmonic metals are available, which limits the spectral range where these strong optical effects ca ...

Wiley-V C H Verlag Gmbh2022

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

The Polarity Reversal of Lightning‐Generated Sky Wave

Farhad Rachidi-Haeri, Marcos Rubinstein, Mohammad Azadifar, Wenhao Hou

The polarity reversal of the lightning‐generated first sky wave as a function of the observation distance is studied using a novel approach combining the finite‐difference time domain (FDTD) method and the superposition principle of electromagnetic waves. ...

2020

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

Toralf Scharf, Maryam Yousefi

Far field pattern generation is investigated for thick sinusoidal phase grating under a Gaussian beam illumination to obtain a high field of view. We compare the Fraunhofer approximation with the High-NA propagator and demonstrate that the Fraunhofer appro ...

IEEE2019

Light fields behind microstructures: study of the Babinet-principle in the Fresnel regime

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim, Krishnaparvathy Puthankovilakam

The Babinet’s principle is a general theorem that holds for electromagnetic waves and is often applied to diffraction of light. Diffraction pattern of a body and that of the complement body are compared and the sum of both radiation patterns must be the sa ...

Spie-Int Soc Optical Engineering2017

Scaling effect and its impact on wavelength-scale microlenses

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

We revisit the scaling laws in micro-optical systems to highlight new phenomena arising beyond a conventional optical regime, especially when the size of the system approaches to the operational wavelength. Our goal is to visualize the impact of the scalin ...

Spie-Int Soc Optical Engineering2017

Carbon Nanotube Array Based Binary Gabor Zone Plate Lenses

Sunan Deng

Diffractive zone plates have a wide range of applications from focusing x-ray to extreme UV radiation. The Gabor zone plate, which suppresses the higher-order foci to a pair of conjugate foci, is an attractive alternative to the conventional Fresnel zone p ...

Nature Research2017

Hard-X-ray Zone Plates: Recent Progress

Giorgio Margaritondo

The technology to focus hard-X-rays (photon energy larger than 1-2 keV) has made great progress in the past three years. The progress was particularly spectacular for lenses based on the Fresnel zone plate concept. The spatial resolution notably increased ...

Mdpi Ag2012

Full-field microimaging with 8 keV X-rays achieves a spatial resolutions better than 20 nm

Giorgio Margaritondo

Fresnel zone plates (450 nm thick Au, 25 nm outermost zone width) used as objective lenses in a full field transmission reached a spatial resolution better than 20 nm and 1.5% efficiency with 8 keV photons. Zernike phase contrast was also realized without ...

Optical Society of America2011

Measuring amplitude and phase of light emerging from microstructures with HRIM

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

Ultra high-resolution measurements of amplitude and phase fields emerging from fine period amplitude gratings are presented and discussed. In the axial direction periodically repeated features are found, whose origins are the Talbot effect within the Fresn ...

SPIE Digital Library2011

Photonic Nanojet engineering: Focal point shaping with scattering phenomena of dielectric microspheres

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

We experimentally engineer Nanojets produced by dielectric spheres by varying the illumination and observe the effect with a high-resolution interference microscope (HRIM). Converging and diverging spherical wavefronts and Bessel- Gauss beams are considere ...

SPIE2011

Generation of a high depth of focus with constant transversal spot size using a phase-only pupil filter

Pramod Rastogi

A novel approach is proposed to obtain an extended depth of focus (DoF) in white light with constant transversal spot size within the DoF. It combines a phase-only pupil filter based on multiplexed radial zones with alternating quartic phase functions. The ...

Taylor & Francis2010

Coherence and wavefront characterization of Si-111 monochromators using double-grating interferometry

A study of the coherence and wavefront properties of a pseudo-channel-cut monochromator in comparison with a double-crystal monochromator is presented. Using a double-grating interferometer designed for the hard X-ray regime, the complex coherence factor w ...

2010

Infrared Measurements of the RF Output of 170-GHz/2-MW Coaxial Cavity Gyrotron and Its Phase Retrieval Analysis

Timothy Goodman, Stefano Alberti, Jean-Philippe Hogge

We report the experimental results of the infrared measurements of output RF beam of the European 2-MW 170-GHz coaxial cavity gyrotron for ITER. The output beam profile is measured by the infrared thermographic technique using an infrared camera and a targ ...

2009

Fabrication of Fresnel zone plates for hard X-rays

A method to fabricate gold structures with high aspect ratio is presented. Fresnel zone plates with an outermost zone width of 100nm and structures of 1μm height are fabricated. Preliminary focusing results at an X-ray energy of 8keV are presented and ways ...

2007

Nanometer focusing properties of Fresnel zone plates described by dynamical diffraction theory

The x-ray focusing properties of linear Fresnel zone plates have been derived by solving the Helmholtz equation for the field propagating through the zones. We consider the imaging of a point object into the first diffraction order of a volume zone plate h ...

2006

Numerical reconstruction of digital holograms : application to phase-contrast imaging and microscopy

Etienne Cuche

This thesis presents a new method for the numerical reconstruction of digital holograms recorded in the off-axis configuration using a CCD camera. The propagation of the reconstructed wave front, from the hologram plane to an observation plane, is achieved ...

EPFL2000