Publications associées à Nombre de Fresnel

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, Chaohui Li

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