Y. Elazhari - Academia.edu (original) (raw)
Papers by Y. Elazhari
SPIE Proceedings, 2004
The ESO OWL site survey plan includes the analysis of the astronomical quality of the Atlas mount... more The ESO OWL site survey plan includes the analysis of the astronomical quality of the Atlas mountains in Morocco. In this paper we are preseningt the first long time measurement of optical turbulence at Oukaimeden site. For this work we built an instrument called ADIMM for an Automated Differencial Image Motion Monitor, and we use it to the measure the optical turbulence at the Oukaimeden Site. We are describing the instrument and reporting the first results obtained after six month of working on this project. The results of night-time seeing measurements carried out during the period from Jun 14 up to October 01 2003 are presented. The median and mean values of the seeing for the entire period of observations are respectively 0.75" and 0.84".
Astronomy & Astrophysics, 2001
We describe the principle of an apodization technique for rectangular apertures that can be imple... more We describe the principle of an apodization technique for rectangular apertures that can be implemented using a Michelson or a Mach-Zender interferometer. Using several interferometers, any integer power of cosine functions can be obtained. The technique is considered for application to the Apodized Square Aperture (ASA) concept recently proposed by Nisenson & Papaliolios (2001). Simple analytic expressions for the Point Spread Functions of such apodized apertures are given. For a cosine to the power N apodization, the resulting focal plane amplitude is simply the sum of N + 1 weighted and shifted sine cardinal functions. The interest of such apodized apertures for coronagraphy is investigated. It appears that these apodization functions are very efficient provided that only a central part of the cosine-arch is used. Analytic expressions are derived for the residual amplitude left in an image of the aperture after the coronagraphic experiment. Best results are obtained with a cosine squared apodization.
The OWL@OUKA is the Optical Wide-field patroL (OWL) facility designed and built by Korea Astronom... more The OWL@OUKA is the Optical Wide-field patroL (OWL) facility designed and built by Korea Astronomy and Space Science Institute (KASI) and installed in 2015 at Oukaimeden Observatory. For the first time we used the opportunities offered by this instrument for the detection and monitoring the exoplanets by the transit method. In this work, we present, first, the validation of the OWL@OUKA for the transit method by reporting the observations we have done to calibrate the instrument in order to chose the best exposure time for a given star. We report on the results obtained form the first observations, in V filter, of a known transit event of the planet Qatar-1b, a hot Jupiter orbiting a metal-rich K dwarf star (Teff = 5013.0, Vmag = 12.84). We have used the software AstroImagJ to reduce the data and the software EXOFASTv2 to fit the transit and extract the planetary parameters, where we obtained a transit depth 0.0207+0.0044 -0.0040 and a planetary radius of 1.09 ± 0.11 RJ , that are i...
We use coherence theory to explain why it is necessary to modify the conventional setup of a Mich... more We use coherence theory to explain why it is necessary to modify the conventional setup of a Michelson interferometer to obtain Haidinger rings with an extended source of white light. The modification consists of introducing a glass slide into one of the two arms of the interferometer. This insertion circumvents the drastic restriction imposed by the low temporal coherence of white light, which prevents the observation of interference rings with the conventional setup. In order to understand this restriction, we developed and implemented a criterion for observing interference fringes. The modified setup also makes it possible to perform a spectral interferometry experiment to analyze the output of the interferometer and determine the refractive index of the glass slide over the whole visible spectrum. The fit of measured data using Sellmeier's law gives the extrapolated value of the refractive index to the IR n_IR=1.5307±0.0003 and the value of the characteristic wavelength λ_0=...
Ground-based and Airborne Telescopes V, 2014
ABSTRACT n this paper we present an analysis of the statistical and temporal properties of seeing... more ABSTRACT n this paper we present an analysis of the statistical and temporal properties of seeing and isoplanatic angle measurements obtained with combined Differential Image Motion Monitor (DIMM) and Multi-Aperture Scintillation Sensor (MASS) at Jbel Aklim candidate site for the Eauropean Extremely Large Telescope (E-ELT). These data have been collected from February 2008 to Jun 2010. The overall seeing statistics for Jbel Aklim site are presented, broken into total seeing, free atmosphere seeing and isoplanatic angle, and ground-layer seeing (difference between the total and free-atmosphere seeing). We examine the statistical distributions of seeing measurements and investigate annual and nightly behavior. The properties of the seeing measurements are discussed in terms of the geography and meteorological conditions at Jbel Aklim site. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
In this work we describe an apodization technique of a circular telescope aperture . The apodizat... more In this work we describe an apodization technique of a circular telescope aperture . The apodization procedure introduced here consists of splitting a PSF image into two PSF images, using optical systems, where one of them has undergone a homothety to change its radial dimensions. After a coherent recombination of these two PSFs, we obtain an apodized image. This procedure allows us to reduce the diffraction wings of the PSF with different reduction factors depending on the combination parameters. In laboratory this apodization aproach can be realized by using an interferometric assembly based on Mach-Zender interferometer . We present here the simulation results and we show that the technique HACA reduce the diffraction wings. This technique can be combined with coronagraphy.
Solar Energy Materials and Solar Cells, 1997
... Solar Cells 45 (1997) 341352 anti Solar .dls Optical properties of oxygenated amorphous cadmi... more ... Solar Cells 45 (1997) 341352 anti Solar .dls Optical properties of oxygenated amorphous cadmium telluride thin films MY E1 Azhari a,*, M. Azizan a, A ... Email: sindibad@marocnet.net.ma 09270248 97 17.00 Copyright 1997 Published by Elsevier Science BV All rights reserved. ...
Monthly Notices of the Royal Astronomical Society, 2013
Experimental Astronomy, 2010
Over the past years, several differential image motion monitors (DIMM) have been built almost eve... more Over the past years, several differential image motion monitors (DIMM) have been built almost everywhere. The DIMM instrument is made up of simple material such as telescope, mask, camera. .. , and it is widely used in seeing measurement campaigns. In order to carry out a prospecting campaign, for the European Extremely Large Telescope (ELT) project, in the Moroccan High Atlas, we have built a new DIMM instrument in our laboratory. To characterize this instrument, we have carried out a crosscalibration between DIMM monitors using different configurations. In this paper we will present the results of those various experiments respectively at Oukaimden site and at the "École Normal Supérieure" (ENS) in the city of Marrakech.
Monthly Notices of the Royal Astronomical Society, 2010
In this paper we describe a two-dimensional apodization of a circular aperture produced by interf... more In this paper we describe a two-dimensional apodization of a circular aperture produced by interferometry. The light that is diffracted by a circular aperture is split into two beams of different amplitudes, where one of them has undergone a homothety to change its radial dimensions using an afocal optical system. The two beams are then combined coherently to form an apodized point-spread function (PSF). This procedure allows us to reduce the diffraction wings of the PSF, with different reduction factors depending on the combination of parameters.
Le travail presente dans cette these s'inscrit dans le cadre de l'etude des proprietes de... more Le travail presente dans cette these s'inscrit dans le cadre de l'etude des proprietes des couches minces de materiaux semi-conducteurs a base de tellurure de cadmium CdTe. L'etude de l'influence de differents parametres de depot sur les proprietes des couches minces de CdTe nous a permis de mettre au point une methode de preparation d'un nouveau materiau a base de CdTe. Il s'agit du tellurure de cadmium amorphe oxygene aCddTe:O. Le depot de couches minces de a-CdTe:O a partir d'une cible polycristalline de CdTe necessite l'utilisation d'un plasma a haut pouvoir oxydant. Le plasma que nous avons utilise est obtenu a partir d'un melange d'argon Ar, de dioxygene et de diazote soumis a un champ electrique radiofrequence de 13,56 MHz. Nous avons montre que le diazote joue un role de catalyseur de l'oxydation de CdTe dans le plasma de deposition dont la composition determine celle des couches minces de a-CdTe:O. En effet, la teneur en oxyge...
In recent years, the transit of HD189733b is the most observed among all known transiting exoplan... more In recent years, the transit of HD189733b is the most observed among all known transiting exoplanets. The transmission spec-trum of this planet has been measured with several instruments from Spitzer and Hubble (HST) Space Telescopes, and from sev-eral ground-based telescopes. In this paper an analytical theory is used to complete this spectrum from near-ultraviolet to infrared (0.33- 7.85 µm). The model suggests a new approach which take into account the quantity of light transmitted through the plane-tary atmosphere and the thermal emissions from the night side of the planet, to describe the transmission spectrum of HD189733b in photometric study. The availability of measures in different wave-lengths has allowed us to validate our model with more efficiency. We found an agreement between our transmission spectrum model of HD189733b and data from the infrared to the UV. The model
We use coherence theory to explain why it is necessary to modify the conventional setup of a Mich... more We use coherence theory to explain why it is necessary to modify the conventional setup of a Michelson interferometer to obtain Haidinger rings with an extended source of white light. The modification consists of introducing a glass slide into one of the two arms of the interferometer. This insertion circumvents the drastic restriction imposed by the low temporal coherence of white light, which prevents the observation of interference rings with the conventional setup. In order to understand this restriction, we developed and implemented a criterion for observing interference fringes. The modified setup also makes it possible to perform a spectral interferometry experiment to analyze the output of the interferometer and determine the refractive index of the glass slide over the whole visible spectrum. The fit of measured data using Sellmeier’s law gives the extrapolated value of the refractive index to the IR nIR = 1.5307 ± 0.0003 and the value of the characteristic wavelength λ0 = ...
Thin Solid Films, 2000
Cadmium telluride oxide CdTeO3 thin films were prepared by r.f.-sputtering from a polycrystalline... more Cadmium telluride oxide CdTeO3 thin films were prepared by r.f.-sputtering from a polycrystalline CdTe target in an atmosphere of nitrogen and oxygen. X-ray diffraction (XRD) analysis showed that the as-deposited samples were amorphous. X-ray photoelectron spectroscopy (XPS) measurements revealed that the films were nearly stoichiometric. The resistivity and the static dielectric constant of the as-deposited layers were found to be
In this laboratory experiment, we study the possibility of producing an apodization of the pupil ... more In this laboratory experiment, we study the possibility of producing an apodization of the pupil of a telescope using a classical Michelson interferometer. To simulate the star, we successively used a Laser source, a source of spectral light and a source of white light. Our goal is to study the performance of the assembly with polychromatic light. We present the results of experiments carried out with a rectangular aperture using a HeNe Laser and Na spectral light sources.
L'adjonction d’un capteur à barrette photosensible à un interféromètre de Michelson réglé en ... more L'adjonction d’un capteur à barrette photosensible à un interféromètre de Michelson réglé en coin d’air permet de réaliser très facilement des expériences de spectrométrie par transformée de Fourier. Le montage proposé dans cet article permet de transformer cette manipulation réputée difficile, en une manipulation de démonstration de cours. Elle peut ainsi facilement être utilisée pour illustrer un certain nombre de concepts fondamentaux en optique, dans une manipulation du type « montage de physique » ou même « leçon de physique » à l’oral de l’agrégation de physique par exemple. Nous avons exploité cette manipulation pour relever les spectres de différentes sources disponibles dans un laboratoire d’enseignement. Ceci nous a permis d’étudier l’influence de divers paramètres sur ces spectres, tels que la nature des verres optiques utilisés, l’utilisation de filtres atténuateurs (neutres ou polariseurs). Ce dispositif permet également un relevé aisé de spectres de régimes transit...
Solar Energy Materials and Solar Cells, 1997
... Solar Cells 45 (1997) 341352 anti Solar .dls Optical properties of oxygenated amorphous cadmi... more ... Solar Cells 45 (1997) 341352 anti Solar .dls Optical properties of oxygenated amorphous cadmium telluride thin films MY E1 Azhari a,*, M. Azizan a, A ... Email: sindibad@marocnet.net.ma 09270248 97 17.00 Copyright 1997 Published by Elsevier Science BV All rights reserved. ...
SPIE Proceedings, 2004
The ESO OWL site survey plan includes the analysis of the astronomical quality of the Atlas mount... more The ESO OWL site survey plan includes the analysis of the astronomical quality of the Atlas mountains in Morocco. In this paper we are preseningt the first long time measurement of optical turbulence at Oukaimeden site. For this work we built an instrument called ADIMM for an Automated Differencial Image Motion Monitor, and we use it to the measure the optical turbulence at the Oukaimeden Site. We are describing the instrument and reporting the first results obtained after six month of working on this project. The results of night-time seeing measurements carried out during the period from Jun 14 up to October 01 2003 are presented. The median and mean values of the seeing for the entire period of observations are respectively 0.75" and 0.84".
Astronomy & Astrophysics, 2001
We describe the principle of an apodization technique for rectangular apertures that can be imple... more We describe the principle of an apodization technique for rectangular apertures that can be implemented using a Michelson or a Mach-Zender interferometer. Using several interferometers, any integer power of cosine functions can be obtained. The technique is considered for application to the Apodized Square Aperture (ASA) concept recently proposed by Nisenson & Papaliolios (2001). Simple analytic expressions for the Point Spread Functions of such apodized apertures are given. For a cosine to the power N apodization, the resulting focal plane amplitude is simply the sum of N + 1 weighted and shifted sine cardinal functions. The interest of such apodized apertures for coronagraphy is investigated. It appears that these apodization functions are very efficient provided that only a central part of the cosine-arch is used. Analytic expressions are derived for the residual amplitude left in an image of the aperture after the coronagraphic experiment. Best results are obtained with a cosine squared apodization.
The OWL@OUKA is the Optical Wide-field patroL (OWL) facility designed and built by Korea Astronom... more The OWL@OUKA is the Optical Wide-field patroL (OWL) facility designed and built by Korea Astronomy and Space Science Institute (KASI) and installed in 2015 at Oukaimeden Observatory. For the first time we used the opportunities offered by this instrument for the detection and monitoring the exoplanets by the transit method. In this work, we present, first, the validation of the OWL@OUKA for the transit method by reporting the observations we have done to calibrate the instrument in order to chose the best exposure time for a given star. We report on the results obtained form the first observations, in V filter, of a known transit event of the planet Qatar-1b, a hot Jupiter orbiting a metal-rich K dwarf star (Teff = 5013.0, Vmag = 12.84). We have used the software AstroImagJ to reduce the data and the software EXOFASTv2 to fit the transit and extract the planetary parameters, where we obtained a transit depth 0.0207+0.0044 -0.0040 and a planetary radius of 1.09 ± 0.11 RJ , that are i...
We use coherence theory to explain why it is necessary to modify the conventional setup of a Mich... more We use coherence theory to explain why it is necessary to modify the conventional setup of a Michelson interferometer to obtain Haidinger rings with an extended source of white light. The modification consists of introducing a glass slide into one of the two arms of the interferometer. This insertion circumvents the drastic restriction imposed by the low temporal coherence of white light, which prevents the observation of interference rings with the conventional setup. In order to understand this restriction, we developed and implemented a criterion for observing interference fringes. The modified setup also makes it possible to perform a spectral interferometry experiment to analyze the output of the interferometer and determine the refractive index of the glass slide over the whole visible spectrum. The fit of measured data using Sellmeier's law gives the extrapolated value of the refractive index to the IR n_IR=1.5307±0.0003 and the value of the characteristic wavelength λ_0=...
Ground-based and Airborne Telescopes V, 2014
ABSTRACT n this paper we present an analysis of the statistical and temporal properties of seeing... more ABSTRACT n this paper we present an analysis of the statistical and temporal properties of seeing and isoplanatic angle measurements obtained with combined Differential Image Motion Monitor (DIMM) and Multi-Aperture Scintillation Sensor (MASS) at Jbel Aklim candidate site for the Eauropean Extremely Large Telescope (E-ELT). These data have been collected from February 2008 to Jun 2010. The overall seeing statistics for Jbel Aklim site are presented, broken into total seeing, free atmosphere seeing and isoplanatic angle, and ground-layer seeing (difference between the total and free-atmosphere seeing). We examine the statistical distributions of seeing measurements and investigate annual and nightly behavior. The properties of the seeing measurements are discussed in terms of the geography and meteorological conditions at Jbel Aklim site. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
In this work we describe an apodization technique of a circular telescope aperture . The apodizat... more In this work we describe an apodization technique of a circular telescope aperture . The apodization procedure introduced here consists of splitting a PSF image into two PSF images, using optical systems, where one of them has undergone a homothety to change its radial dimensions. After a coherent recombination of these two PSFs, we obtain an apodized image. This procedure allows us to reduce the diffraction wings of the PSF with different reduction factors depending on the combination parameters. In laboratory this apodization aproach can be realized by using an interferometric assembly based on Mach-Zender interferometer . We present here the simulation results and we show that the technique HACA reduce the diffraction wings. This technique can be combined with coronagraphy.
Solar Energy Materials and Solar Cells, 1997
... Solar Cells 45 (1997) 341352 anti Solar .dls Optical properties of oxygenated amorphous cadmi... more ... Solar Cells 45 (1997) 341352 anti Solar .dls Optical properties of oxygenated amorphous cadmium telluride thin films MY E1 Azhari a,*, M. Azizan a, A ... Email: sindibad@marocnet.net.ma 09270248 97 17.00 Copyright 1997 Published by Elsevier Science BV All rights reserved. ...
Monthly Notices of the Royal Astronomical Society, 2013
Experimental Astronomy, 2010
Over the past years, several differential image motion monitors (DIMM) have been built almost eve... more Over the past years, several differential image motion monitors (DIMM) have been built almost everywhere. The DIMM instrument is made up of simple material such as telescope, mask, camera. .. , and it is widely used in seeing measurement campaigns. In order to carry out a prospecting campaign, for the European Extremely Large Telescope (ELT) project, in the Moroccan High Atlas, we have built a new DIMM instrument in our laboratory. To characterize this instrument, we have carried out a crosscalibration between DIMM monitors using different configurations. In this paper we will present the results of those various experiments respectively at Oukaimden site and at the "École Normal Supérieure" (ENS) in the city of Marrakech.
Monthly Notices of the Royal Astronomical Society, 2010
In this paper we describe a two-dimensional apodization of a circular aperture produced by interf... more In this paper we describe a two-dimensional apodization of a circular aperture produced by interferometry. The light that is diffracted by a circular aperture is split into two beams of different amplitudes, where one of them has undergone a homothety to change its radial dimensions using an afocal optical system. The two beams are then combined coherently to form an apodized point-spread function (PSF). This procedure allows us to reduce the diffraction wings of the PSF, with different reduction factors depending on the combination of parameters.
Le travail presente dans cette these s'inscrit dans le cadre de l'etude des proprietes de... more Le travail presente dans cette these s'inscrit dans le cadre de l'etude des proprietes des couches minces de materiaux semi-conducteurs a base de tellurure de cadmium CdTe. L'etude de l'influence de differents parametres de depot sur les proprietes des couches minces de CdTe nous a permis de mettre au point une methode de preparation d'un nouveau materiau a base de CdTe. Il s'agit du tellurure de cadmium amorphe oxygene aCddTe:O. Le depot de couches minces de a-CdTe:O a partir d'une cible polycristalline de CdTe necessite l'utilisation d'un plasma a haut pouvoir oxydant. Le plasma que nous avons utilise est obtenu a partir d'un melange d'argon Ar, de dioxygene et de diazote soumis a un champ electrique radiofrequence de 13,56 MHz. Nous avons montre que le diazote joue un role de catalyseur de l'oxydation de CdTe dans le plasma de deposition dont la composition determine celle des couches minces de a-CdTe:O. En effet, la teneur en oxyge...
In recent years, the transit of HD189733b is the most observed among all known transiting exoplan... more In recent years, the transit of HD189733b is the most observed among all known transiting exoplanets. The transmission spec-trum of this planet has been measured with several instruments from Spitzer and Hubble (HST) Space Telescopes, and from sev-eral ground-based telescopes. In this paper an analytical theory is used to complete this spectrum from near-ultraviolet to infrared (0.33- 7.85 µm). The model suggests a new approach which take into account the quantity of light transmitted through the plane-tary atmosphere and the thermal emissions from the night side of the planet, to describe the transmission spectrum of HD189733b in photometric study. The availability of measures in different wave-lengths has allowed us to validate our model with more efficiency. We found an agreement between our transmission spectrum model of HD189733b and data from the infrared to the UV. The model
We use coherence theory to explain why it is necessary to modify the conventional setup of a Mich... more We use coherence theory to explain why it is necessary to modify the conventional setup of a Michelson interferometer to obtain Haidinger rings with an extended source of white light. The modification consists of introducing a glass slide into one of the two arms of the interferometer. This insertion circumvents the drastic restriction imposed by the low temporal coherence of white light, which prevents the observation of interference rings with the conventional setup. In order to understand this restriction, we developed and implemented a criterion for observing interference fringes. The modified setup also makes it possible to perform a spectral interferometry experiment to analyze the output of the interferometer and determine the refractive index of the glass slide over the whole visible spectrum. The fit of measured data using Sellmeier’s law gives the extrapolated value of the refractive index to the IR nIR = 1.5307 ± 0.0003 and the value of the characteristic wavelength λ0 = ...
Thin Solid Films, 2000
Cadmium telluride oxide CdTeO3 thin films were prepared by r.f.-sputtering from a polycrystalline... more Cadmium telluride oxide CdTeO3 thin films were prepared by r.f.-sputtering from a polycrystalline CdTe target in an atmosphere of nitrogen and oxygen. X-ray diffraction (XRD) analysis showed that the as-deposited samples were amorphous. X-ray photoelectron spectroscopy (XPS) measurements revealed that the films were nearly stoichiometric. The resistivity and the static dielectric constant of the as-deposited layers were found to be
In this laboratory experiment, we study the possibility of producing an apodization of the pupil ... more In this laboratory experiment, we study the possibility of producing an apodization of the pupil of a telescope using a classical Michelson interferometer. To simulate the star, we successively used a Laser source, a source of spectral light and a source of white light. Our goal is to study the performance of the assembly with polychromatic light. We present the results of experiments carried out with a rectangular aperture using a HeNe Laser and Na spectral light sources.
L'adjonction d’un capteur à barrette photosensible à un interféromètre de Michelson réglé en ... more L'adjonction d’un capteur à barrette photosensible à un interféromètre de Michelson réglé en coin d’air permet de réaliser très facilement des expériences de spectrométrie par transformée de Fourier. Le montage proposé dans cet article permet de transformer cette manipulation réputée difficile, en une manipulation de démonstration de cours. Elle peut ainsi facilement être utilisée pour illustrer un certain nombre de concepts fondamentaux en optique, dans une manipulation du type « montage de physique » ou même « leçon de physique » à l’oral de l’agrégation de physique par exemple. Nous avons exploité cette manipulation pour relever les spectres de différentes sources disponibles dans un laboratoire d’enseignement. Ceci nous a permis d’étudier l’influence de divers paramètres sur ces spectres, tels que la nature des verres optiques utilisés, l’utilisation de filtres atténuateurs (neutres ou polariseurs). Ce dispositif permet également un relevé aisé de spectres de régimes transit...
Solar Energy Materials and Solar Cells, 1997
... Solar Cells 45 (1997) 341352 anti Solar .dls Optical properties of oxygenated amorphous cadmi... more ... Solar Cells 45 (1997) 341352 anti Solar .dls Optical properties of oxygenated amorphous cadmium telluride thin films MY E1 Azhari a,*, M. Azizan a, A ... Email: sindibad@marocnet.net.ma 09270248 97 17.00 Copyright 1997 Published by Elsevier Science BV All rights reserved. ...