PSF and field of view characteristics of imaging and nulling interferometers

In this communication are presented some complements to a recent paper entitled "Simple Fourier optics formalism for high angular resolution systems and nulling interferometry", dealing with imaging and nulling capacities of a few types of multi-aperture optical systems. Herein the characteristics of such systems in terms of Point Spread Function (PSF) and Field of View (FoV) are derived from simple analytical expressions that are further evaluated numerically for various configurations. We consider successively the general cases of Fizeau and Michelson interferometers, and those of a monolithic pupil, nulling telescope, of a nulling, Sheared-Pupil Telescope (SPT), and of a sparse aperture, Axially Combined Interferometer (ACI). The analytical formalism also allows establishing the exact Object-Image relationships applicable to nulling PSTs or ACIs that are planned for future space missions searching for habitable extra-solar planets

Multi-spectral piston sensor for co-phasing giant segmented mirrors and multi-aperture interferometric arrays

This paper presents the optical design of a multi-spectral piston sensor suitable to co-phasing giant segmented mirrors equipping the Future Extremely Large Telescopes (ELTs). The general theory of the sensor is described in detail and numerical simulations have been carried out, demonstrating that direct piston and tip-tilt measurements are feasible within accuracies respectively close to 20 nm and 10 nano-radians. Those values are compatible with the co-phasing requirements, although the method seems to be perturbed by uncorrected atmospheric seein

La conciliation de la "Charte des droits et libertés de la personne" et du "Code civil du Québec" en matière de diffamation

La principale tâche d’un tribunal appelé à se prononcer dans le contexte d’un recours en diffamation est de parvenir à concilier les droits fondamentaux des parties qui s’opposent. Seule la présence d’une rupture d’équilibre entre le droit à la sauvegarde de la dignité, de l’honneur et de la réputation, d’une part, et la liberté d’expression, d’autre part, justifiera l’attribution d’une réparation. Au Québec, suivant le raisonnement de la Cour suprême du Canada dans l’arrêt Béliveau St-Jacques, les tribunaux s’en remettent aux principes du droit commun de la responsabilité civile prévus au Code civil pour déterminer s’il y a eu ou non diffamation. Le présent mémoire a pour objet de vérifier si cette approche est conforme au statut et à l’objet respectifs de la Charte des droits et libertés de la personne [Charte québécoise] et du Code civil du Québec dans l’ordre juridique québécois. Il vise, plus généralement, à vérifier comment ces instruments juridiques devraient interagir en matière de diffamation compte tenu de leur statut hiérarchique, de leur rôle et du libellé de leurs dispositions. Nos recherches démontrent que le fait d’assimiler le recours en diffamation fondé sur des droits contenus dans la Charte québécoise à un recours en responsabilité civile de droit commun fondé sur le Code civil du Québec est incompatible avec la place prépondérante que doit occuper la Charte québécoise dans l’ordre juridique québécois, avec son objet réparateur et avec son texte. La Charte fournit les outils nécessaires à la conciliation efficace des droits qui s’opposent dans un recours en diffamation. Par conséquent, en cette matière, le Code ne devrait s’appliquer qu’à titre supplétif, conformément à son statut par rapport à la Charte.In a defamation action, the court’s main duty is to reconcile the fundamental rights of the opposing parties. The court will award a remedy only if a break in the balance between the right to the safeguard of dignity, honour and reputation, on the one hand, and freedom of expression, on the other, is established. In Quebec, following the Supreme Court of Canada’s reasoning in the case Béliveau St-Jacques, courts mostly rely on the general principles of civil liability provided by the Civil Code of Québec to determine the existence of defamation. The object of the present master’s thesis is to ascertain whether this approach is consistent with the respective status and purpose of the Charter of Human Rights and Freedoms [Quebec Charter] and the Civil Code of Québec in the Quebec legal system. More generally, it seeks to verify how these legal instruments should interact in the context of defamation in the light of their hierarchical status and of their role. Our study demonstrates that to assimilate a defamation action, based on fundamental rights included in the Quebec Charter, to an action based on the general principles of civil liability is incompatible with the preponderant place that must occupy the Charter in the legal hierarchy of Québec and with its remedial purpose. The Charter provides the necessary tools for the effective reconciliation of the fundamental rights in defamation proceedings. Consequently, in this matter, the Civil Code of Québec should only be applied in a suppletive manner, in accordance with its status in relation to the Charter

Wavefront sensor based on varying transmission filters: theory and expected performance

The use of Wavefront Sensors (WFS) is nowadays fundamental in the field of instrumental optics. This paper discusses the principle of an original and recently proposed new class of WFS. Their principle consists in evaluating the slopes of the wavefront errors by means of varying density filters placed into the image plane of the tested optical system. The device, sometimes called 'optical differentiation WFS' is completed by a digital data-processing system reconstructing the wavefront from the obtained slopes. Various luminous sources of different wavelengths and spectral widths can be employed. The capacities of the method are discussed from the geometrical and Fourier optics points of view, then by means of numerical simulations showing that the ultimate accuracy can be well below lambda/10 and lambda/100 Peak-to-Valley (PTV) and RMS respectively, provided that certain precautions are taken.Comment: 2 tables, 6 figure

Predicting leakage of the VERCORS mock-up and concrete containment buildings - a digital twin approach

EDF operates a nuclear power generation fleet made up of 56 reactors. This fleet contains 24 reactors designed as double-walled concrete containment building. The inner concrete containment vessel has no metallic liner and is a prestressed reinforced concrete building. The inner concrete containment vessel is designed to withstand a severe accident, in terms of mechanical and sealing behaviour. The tightness of the containment is tested every 10 years, by carrying out a pressurization test and by measuring the leak rate. The leak rate is required to be below a regulatory threshold to continue operation of the concrete containment building for the next ten years. Ageing of concrete due to drying, creep and shrinkage leads to increase prestress loss and then leak rate with time. For some containment buildings, the leak rate gets closer to the regulatory threshold with time, so important coating programs are planned to mitigate and limit the leak rate under the regulatory threshold. Therefore, it is very important for EDF to have a concrete containment building leak rate prediction tool. To address this issue, an important research program around a 1/3 scale concrete containment building mock-up called "VERCORS" have been launched at EDF. The mock-up is heavily instrumented, and its materials (concrete, prestressing cables) have been widely characterized and studied. An important numerical effort has also been made to implement structural computations of the mock-up and to capitalize these computations as well as their post-processing (so as to compare automatically with the monitoring data) in what can be called a digital twin of the mock-up. This digital twin is now used to predict the leakage of VERCORS mock-up before yearly pressure test, and also to optimize the repair programs on the real containments

The planar optics phase sensor: a study for the VLTI 2nd generation fringe tracker

In a few years, the second generation instruments of the Very Large Telescope Interferometer (VLTI) will routinely provide observations with 4 to 6 telescopes simultaneously. To reach their ultimate performance, they will need a fringe sensor capable to measure in real time the randomly varying optical paths differences. A collaboration between LAOG (PI institute), IAGL, OCA and GIPSA-Lab has proposed the Planar Optics Phase Sensor concept to ESO for the 2[SUP]nd[/SUP] Generation Fringe Tracker. This concept is based on the integrated optics technologies, enabling the conception of extremely compact interferometric instruments naturally providing single-mode spatial filtering. It allows operations with 4 and 6 telescopes by measuring the fringes position thanks to a spectrally dispersed ABCD method. We present here the main analysis which led to the current concept as well as the expected on-sky performance and the proposed design

MAORY for ELT: preliminary design overview

MAORY is one of the approved instruments for the European Extremely Large Telescope. It is an adaptive optics module, enabling high-angular resolution observations in the near infrared by real-time compensation of the wavefront distortions due to atmospheric turbulence and other disturbances such as wind action on the telescope. An overview of the instrument design is given in this paper

The MAORY first-light adaptive optics module for E-ELT

The MAORY adaptive optics module is part of the first light instrumentation suite for the E-ELT. The MAORY project phase B is going to start soon. This paper contains a system-level overview of the current instrument design