Publications associées à Optical characterization of fully programmable MEMS diffraction gratings

Engineering Absorption for Foil Applications

Light matter interactions such as extinction, reflection, and transmission can be described by classical optics. Dur-ing the past decades, research focused on a novel resonant extinction type called plasmonics that allows for en-hancement of both types of ...

EPFL2022

Pitfalls in the spectral measurements of polarization-altering metasurfaces

Olivier Martin, Hsiang-Chu Wang

The optical characterization of metasurfaces and nanostructures that alter the polarization of light is tricky and can lead to unphysical results, such as reflectance beyond unity. We track the origin of such pitfalls to the response of some typical optica ...

Optica Publishing Group2022

Prototype mitre bends of the ex-vessel waveguide system for the ITER upper launcher: Thermal hydraulic simulations and experiments with off-center mm-wave beams

René Chavan, Timothy Goodman, Matteo Vagnoni, Anastasia Xydou, Humberto Torreblanca Quiroz

On ITER, long pulse gyrotrons are required as a power source for electron cyclotron heating (ECH) and current drive (CD). The microwaves are guided from the gyrotrons, which are placed far from the Tokamak, into the plasma by transmission lines (TLs) and a ...

2021

Electromagnetic and mechanical analyses of the ITER electron cyclotron Upper launcher steering M4 mirrors for the vertical displacement event

René Chavan, Timothy Goodman, Avelino Mas Sanchez, Matteo Vagnoni

The mm-wave power exiting the eight In-Vessel waveguides inside the ITER Electron Cyclotron Upper Launcher is reflected by three fixed mirror sets and finally aimed by two independent steering mirrors to specific plasma locations. A design solution for bot ...

2020

Surface-based luminescence measurement substrate

Raphaël Barbey, Nicolas Maxime André Descharmes

Surface-based measurement substrate including: • - at least one optical cavity layer (7); • - a first optical mirror (9) and a second optical mirror (11), the first and second optical mirrors enclosing the optical cavity layer and defining an optical cavit ...

2020

TCV mirrors cleaned by plasma

Stefano Coda

Metallic mirrors exposed in TCV tokamak were cleaned by plasma in laboratory. A gold (Au) mirror was deposited with 185-285 nm of amorphous carbon (aC:D) film coming from the carbon tiles of TCV. Another molybdenum (Mo) mirror had a thicker deposit due to ...

Elsevier2017

Back-Propagating the Light of Field Stars to Probe Telescope Mirrors Aberrations

Michaël Unser, Frédéric Courbin, Ferréol Arnaud Marie Soulez

We propose a wavefront-based method to estimate the PSF over the whole field of view. This method estimate the aberrations of all the mirrors of the telescope using only field stars. In this proof of concept paper, we described the method and present some ...

SPIE2016

Plasma cleaning of beryllium coated mirrors

Cleaning systems of metallic first mirrors are needed in more than 20 optical diagnostic systems from ITER to avoid reflectivity losses. Currently, plasma sputtering is considered as one of the most promising techniques to remove deposits coming from the m ...

Iop Publishing Ltd2016

New diagnostics for density measurement on Frascati Tokamak upgrade

Fabio Avino, Anton Petrov

In FTU, density profile is measured with two new diagnostics: a CO2/CO scanning interferometer and a time-of-flight radar (denominated refractometer). The first, using two scanning beams, can provide a plasma density profile every 62.5 mu s. Two lasers (CO ...

Elsevier Science Bv2013

Large Hybrid High Precision MEMS Mirrors

Dara Zaman Bayat

This thesis presents the design and microfabrication technology of a tip-tilt, 2 degree of freedom "mirror system" made out of Silicon On Insulator (SOI) wafers with two movable mirrors that have diameter of 10 mm. The system was intended for precise beam ...

EPFL2011

Diagnostic mirrors for ITER: A material choice and the impact of erosion and deposition on their performance

Richard Pitts

Metal mirrors will be implemented in about half of the ITER diagnostics. Mirrors in ITER will have to withstand radiation loads, erosion by charge-exchange neutrals, deposition of impurities, particle implantation and neutron irradiation. It is believed th ...

2007

Multiple scattering in optical coherence tomography. I. Investigation and modeling

Stéphane Bourquin, Boris Clément Karamata, Marcel Leutenegger, Theo Lasser, Markus Laubscher

We present a new model of optical coherence tomography (OCT) taking into account multiple scattering. A theoretical analysis and experimental investigation reveals that in OCT, despite multiple scattering, the field backscattered from the sample is general ...

2005