Influence of the pinhole size on the resolution of the 4Pi' microscope studied by means of the optical transfer function

Optical transfer functions are presented for the 4pi' microscope. The effects of the size of the confocal pinhole on the three-dimensional resolution are studied. It is shown that the resolution of the 4Pi' microscope depends weakly on the pinhole size. This result suggest that the pinhole can be removed in order to increase the signal-to-noise ratio

An observable prerequisite for the existence of persistent currents

A classical model is presented for persistent currents in superconductors. Their existence is argued to be warranted because their decay would violate the second law of thermodynamics. This conclusion is achieved by analyzing comparatively Ohm's law and the Joule effect in normal metals and superconducting materials. Whereas Ohm's law applies in identical terms in both cases, the Joule effect is shown to cause the temperature of a superconducting sample to \textit{decrease}. An experiment is proposed to check the validity of this work in superconductors of both types I and II.Comment: 11 pages, 4 figure

Study of the skin effect in superconducting materials

The skin effect is analyzed to provide the numerous measurements of the penetration depth of the electromagnetic field in superconducting materials with a theoretical basis. Both the normal and anomalous skin effects are accounted for within a single framework. The emphasis is laid on the conditions required for the penetration depth to be equal to London's length, which enables us to validate an assumption widely used in the interpretation of all current experimental results.Comment: 4 pages, 2 figures. arXiv admin note: text overlap with arXiv:1507.0333

Revisiting low-frequency susceptibility data in superconducting materials

Old susceptibility data, measured in superconducting materials at low-frequency, are shown to be accounted for consistently within the framework of a recently published\cite{sz1} analysis of the skin effect. Their main merit is to emphasize the significance of the skin-depth measurements, performed \textit{just beneath} the critical temperature $T_c$, in order to disprove an assumption, which thwarted any understanding of the skin-depth data, achieved so far by conventional high-frequency methods, so that those data might, from now on, give access to the temperature dependence of the concentration of superconducting electrons.Comment: 7 pages, 4 figure

Arrangement of a 4Pi microscope for reducing the confocal detection volume with two-photon excitation

The main advantage of two-photon fluorescence confocal microscopy is the low absorption obtained with live tissues at the wavelengths of operation. However, the resolution of two-photon fluorescence confocal microscopes is lower than in the case of one-photon excitation. The 4Pi microscope type C working in two-photon regime, in which the excitation beams are coherently superimposed and, simultaneously, the emitted beams are also coherently added, has shown to be a good solution for increasing the resolution along the optical axis and for reducing the amplitude of the side lobes of the point spread function. However, the resolution in the transverse plane is poorer than in the case of one-photon excitation due to the larger wavelength involved in the two-photon fluorescence process. In this paper we show that a particular arrangement of the 4Pi microscope, referenced as 4Pi0 microscope, is a solution for obtaining a lateral resolution in the two-photon regime similar or even better to that obtained with 4Pi microscopes working in the one-photon excitation regime

Compte-rendu du colloque : « John Carpenter, “maître de l’horreur” »

Organisé par Mélanie Boissonneau, Quentin Mazel, Thomas Pillard (IRCAV, Université Sorbonne Nouvelle – Paris 3) et Gaspard Delon (CERILAC, Université Paris Diderot), le colloque international « John Carpenter, “maître de l’horreur” » s’est déroulé les 30 et 31 octobre 2019 à l’Université Paris Diderot. Il comptait 17 interventions qui ont exploré l’œuvre du cinéaste selon des approches diverses, en éclairant sous un nouveau jour un certain nombre de ses films les plus connus (The Thing, Chris..

Congrès AFECCAV 2016 (6-8 juillet 2016) : « Images pour/suite : remake, franchise, filiation ».

Organisé par Jean-François Baillon, Pierre Beylot, Camille Gendrault, Alain Kleinberger, Barbara Laborde, Gwénaëlle Le Gras, Raphaëlle Moine, Geneviève Sellier et Benjamin Thomas, le congrès 2016 de l’AFECCAV intitulé « Image pour/suite : remake, franchise, filiation », accueilli par l’Université Bordeaux Montaigne, s’est déroulé dans les locaux de la MSHA du 6 au 8 juillet. Reflétant la politique de l’association, qui s’efforce notamment d’accompagner les doctorants et les jeunes docteurs da..

Far-field radiation pattern in Coherent Anti-stokes Raman Scattering (CARS) Microscopy

Far field radiation pattern under tight focusing condition is investigated in Coherent Anti-stokes Raman Scattering (CARS) microscopy both in the forward (F-CARS) and backward (E-CARS) directions. While we assume no refraction index mismatch between the sample and the environing medium, our rigorous numerical electromagnetic computation takes into account the exact polarizations of the excitation laser beams and of the induced nonlinear dipoles. F-CARS and E-CARS radiation patterns, as well as their divergence, are studied as a function of the size of the sample object and compared to the excitation beams