In 1996, Jean Gay and Yves Rabbia presented their Achromatic Interferential Coronagraph (AIC) for... more In 1996, Jean Gay and Yves Rabbia presented their Achromatic Interferential Coronagraph (AIC) for detecting and imaging faint companions (ultimately exoplanets) in the neighboring of a star. As presented then, the Michleson-like Interferometer configuration of the AIC hardens its insertion into an existing (coaxial) optical train, the output beam of the AIC being delivered at right angle from the input beam. To overcome this, they reconfigured the AIC into a compact and fully axial coronagraph, the CIAXE, which main feature consists of using two thick lenses machined in the same optical material. For the CIAXE to deliver the output beam along the same axis as the input beam, the two lenses are coaxially disposed on the optical axis and are separated, at their common spherical contact surface by a thin air gap acting like a beam splitter. We have set up a laboratory experiment aiming at validating the principle of the concept. Our first step was to equalize the thicknesses of the two lenses, so as to make zero the optical path difference between both arms. For this, the (residual) value of the OPD has been evaluated and then the lenses have been re-machined so as to decrease as far as technologically possible, the thicknesses mismatch. As a second step, a micro-controlled rotation around the common curvature center of the spherical surfaces of the lenses is applied. This allows a fine tuning of the residual OPD at the required accuracy level. Are presented here test bench, steps and results.
For the detection and direct imaging of exoplanets, when the intensity ratio between a star and i... more For the detection and direct imaging of exoplanets, when the intensity ratio between a star and its orbiting planet can largely exceed 106, coronagraphic methods are mandatory. In 1996, a concept of achromatic interferocoronagraph (AIC) was presented by J. Gay and Y. Rabbia for the detection of very faint stellar companions, such as exoplanets. In an earlier paper, we presented a modified version of the AIC permitting to determine the relative position of these faint companions with respect to the parent star, a problem unsolved in the original design of the AIC. Our modification lied in the use of cylindrical lens doublets as field rotator. By placing two of them in one arm of the interferometric set-up of AIC, we destroyed the axis of symmetry induced by the AIC's original design. Our theoretical study, along with the numerical computations, presented then, and the preliminary test bench results aiming at validating the cylindrical lens doublet field rotation capability, presented in this paper, show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optic axis.
In 2004, our group proposed IRAN, an alternative beam-combination technique to the so-called hype... more In 2004, our group proposed IRAN, an alternative beam-combination technique to the so-called hypertelescope imaging method introduced by Labeyrie in the 1990s. We have recently set up a laboratory experiment aiming at validating our image densification approach instead of the pupil densification scheme of Labeyrie. In our experiment, seven sub-apertures illuminated by laser sources are recombined using the IRAN scheme. The validation of the IRAN recombination consists basically in retrieving the point-spread intensity distribution (PSID), demonstrating the conservation of the object-image convolution relation. We will introduce IRAN, compare it to the hyper-telescope, and present the experimental results that we obtained.
Context: For detecting and directly imaging exoplanets, coronagraphic methods are mandatory when ... more Context: For detecting and directly imaging exoplanets, coronagraphic methods are mandatory when the intensity ratio between a star and its orbiting planet can be as large as 10^6. In 1996, a concept of an achromatic interfero-coronagraph (AIC) was presented for detecting very faint stellar companions, such as exoplanets.
Aims: We present a modified version of the AIC not only permitting these faint companions to be detected but also their relative position to be determined with respect to the parent star, a problem that was not solved in the original design of the AIC.
Methods: In our modified design, two cylindrical lens doublets were used to remove the 180° ambiguity introduced by the AIC's original design.
Results: Our theoretical study and the numerical computations show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optical axis.
Proceedings of The International Astronomical Union, Aug 14, 2007
The next generation (post-VLTI) of multi-telescope interferometric arrays operated in optical/inf... more The next generation (post-VLTI) of multi-telescope interferometric arrays operated in optical/infrared wavelengths should be kilometric, from 1 to 10 km. The Concordia station offers a unique opportunity to set such an interferometer in the best atmospheric conditions presently known on Earth.
With the advent of imaging aperture-synthesis spectro-interferometers the search of exoplanetary ... more With the advent of imaging aperture-synthesis spectro-interferometers the search of exoplanetary systems appears within reach of direct detection both from the ground and space as soon as the array are co-phased.
The characteristics of the PSF at the common focus at such arrays is highly dependent on the geometry and the recombination scheme considered for the array. The IRAN recombination, Interferometric Remapped Array Nulling, has been proposed as an alternative to the Fizeau recombination. IRAN keeps intact the high resolution of the entire array given by its longest baseline. And when compared to the Fizeau recombination, IRAN provides a PSF with a much sharper central peak, surrounded by a clean field where direct imaging is possible. I set a laboratory test bench at the H. Fizeau laboratory aiming at validating its concept. The basics of IRAN are recalled in this manuscript followed by the SPIE paper where the experimental results are presented.
In order to improve even further the dynamic range of the PSFs , I propose two conceptual coronagraphic studies, both based on the AIC, Achromatic Interferential Coronagraph of J. Gay and Y. Rabbia. The first concept, also proposed by J. Gay is called CIAXE. It is a reconfiguration of the AIC into a compact and fully axial coronagraph. The motivation behind this reconfiguration it to facilitate the insertion of the coronagraph at the focus of telescopes. The CIAXE main feature consists of using two thick lenses machined in the same optical material separated by a thin air gap acting exactly like a beamsplitter. In this manuscript I recall the basics of the CIAXE and present the experimental results of the test bench I ran in Grasse. I describe, in the context of matrix optics, the derivation of the different surface radii, as well as the method conceived and used to determine the thickness difference between the lenses.
The second concept, APIC, Absolute Position Interfero-Coronagraph. Even though firstly conceived as a modification of the AIC where the 180$^o$ ambiguity is removed, APIC turned out to be a versatile coronagraph in terms of IWA and residual stellar energy. The optic behind this characteristic is cylindrical lens doublet. Apart from inducing achromatic phase shifts at its focus crossing, a cylindrical lens doublet reflects the wave front around the axis of the doublet. Depending on the orientation we give to this axis, an off-axis source's position in the image plan can be easily linked to the real position on the sky. A detailed study of the concept is presented here in the formalism of Fourier optics. The experimental results delivered by the test bench I set at ESO are also presented. They show high fidelity to the theoretical expectations. The versatility of APIC is highlighted through the study of the impact of the doublet's orientation on the IWA of the coronagraph, the intensity distribution of an on axis source and the calibration of its residual energy in the image plane.
Résumé:
Les interféromètres de seconde génération qui avec leur bases pensées à l'échelle kilométrique ouvriront la voie à l'imagerie astronomique à très haute résolution angulaire. Dans cette perspective, il faut commencer par l’étude et l’optimisation de la recombinaison de faisceaux. L’interféromètre KEOPS, Kiloparsec Explorer for Optical Planet Search, fait partie de ces projets ambitieux destinés à permettre l'imagerie à haute résolution angulaire et haute dynamique. La méthode de recombinaison de faisceaux que l’on désire retenir pour KEOPS est IRAN ou Interferometric Remapped Array Nulling. Elle permettra d’exploiter ce large réseau de télescopes en mode imagerie directe à haute résolution angulaire. Je rappelle le principe d'IRAN dans ce manuscrit et je présente les résultats, qui restent perfectible, du montage expérimental.
En termes de haute dynamique je propose deux solutions coronographiques toutes les deux basées sur le principe du CIA, Coronographe Interférentiel Achromatique de J. Gay. Le premier principe est aujourd'hui publié sur le nom d'APIC: ABSOLUTE POSITION INTERFERO-CORONAGRAPH. Si dans la configuration du CIA c'est un oeil de chat qui assure le déphasage et la rotation du champ, dans la configuration d'APIC j'ai opté pour l'utilisation de doublets de lentilles cylindriques. En variant l'orientation des doublets, d'une part, les positions des sous-images dans le plan focal final peuvent être modifiées, l'ambiguïté du CIA se retrouve ainsi supprimée et d'autre part, IWA est amélioré et l'énergie résiduelle d'une étoile dans le plan image réduite. Dans ce manuscrit je présente son principe au moyen du formalisme de Fourier. Et je présente une première étape préliminaire de sa validation expérimentale. L'autre concept coronographique est le CIAXE pour CIA dans l'aXE. C'est l’équipe conceptrice même du CIA qui a pensé à modifier le montage optique de ce dernier afin de faciliter son insertion au foyer de télescopes. Dans ce manuscrit je rappel son principe de fonctionnement en m'appuyant sur l'optique matricielle et je présente les résultats d'une expérience de laboratoire visant à l'identification des points critiques d'un tel montage afin de pouvoir tirer des conclusions pour une version opérationnelle au foyer d'un télescope.
In 1996, Jean Gay and Yves Rabbia presented their Achromatic Interferential Coronagraph (AIC) for... more In 1996, Jean Gay and Yves Rabbia presented their Achromatic Interferential Coronagraph (AIC) for detecting and imaging faint companions (ultimately exoplanets) in the neighboring of a star. As presented then, the Michleson-like Interferometer configuration of the AIC hardens its insertion into an existing (coaxial) optical train, the output beam of the AIC being delivered at right angle from the input beam. To overcome this, they reconfigured the AIC into a compact and fully axial coronagraph, the CIAXE, which main feature consists of using two thick lenses machined in the same optical material. For the CIAXE to deliver the output beam along the same axis as the input beam, the two lenses are coaxially disposed on the optical axis and are separated, at their common spherical contact surface by a thin air gap acting like a beam splitter. We have set up a laboratory experiment aiming at validating the principle of the concept. Our first step was to equalize the thicknesses of the two lenses, so as to make zero the optical path difference between both arms. For this, the (residual) value of the OPD has been evaluated and then the lenses have been re-machined so as to decrease as far as technologically possible, the thicknesses mismatch. As a second step, a micro-controlled rotation around the common curvature center of the spherical surfaces of the lenses is applied. This allows a fine tuning of the residual OPD at the required accuracy level. Are presented here test bench, steps and results.
For the detection and direct imaging of exoplanets, when the intensity ratio between a star and i... more For the detection and direct imaging of exoplanets, when the intensity ratio between a star and its orbiting planet can largely exceed 106, coronagraphic methods are mandatory. In 1996, a concept of achromatic interferocoronagraph (AIC) was presented by J. Gay and Y. Rabbia for the detection of very faint stellar companions, such as exoplanets. In an earlier paper, we presented a modified version of the AIC permitting to determine the relative position of these faint companions with respect to the parent star, a problem unsolved in the original design of the AIC. Our modification lied in the use of cylindrical lens doublets as field rotator. By placing two of them in one arm of the interferometric set-up of AIC, we destroyed the axis of symmetry induced by the AIC's original design. Our theoretical study, along with the numerical computations, presented then, and the preliminary test bench results aiming at validating the cylindrical lens doublet field rotation capability, presented in this paper, show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optic axis.
In 2004, our group proposed IRAN, an alternative beam-combination technique to the so-called hype... more In 2004, our group proposed IRAN, an alternative beam-combination technique to the so-called hypertelescope imaging method introduced by Labeyrie in the 1990s. We have recently set up a laboratory experiment aiming at validating our image densification approach instead of the pupil densification scheme of Labeyrie. In our experiment, seven sub-apertures illuminated by laser sources are recombined using the IRAN scheme. The validation of the IRAN recombination consists basically in retrieving the point-spread intensity distribution (PSID), demonstrating the conservation of the object-image convolution relation. We will introduce IRAN, compare it to the hyper-telescope, and present the experimental results that we obtained.
Context: For detecting and directly imaging exoplanets, coronagraphic methods are mandatory when ... more Context: For detecting and directly imaging exoplanets, coronagraphic methods are mandatory when the intensity ratio between a star and its orbiting planet can be as large as 10^6. In 1996, a concept of an achromatic interfero-coronagraph (AIC) was presented for detecting very faint stellar companions, such as exoplanets.
Aims: We present a modified version of the AIC not only permitting these faint companions to be detected but also their relative position to be determined with respect to the parent star, a problem that was not solved in the original design of the AIC.
Methods: In our modified design, two cylindrical lens doublets were used to remove the 180° ambiguity introduced by the AIC's original design.
Results: Our theoretical study and the numerical computations show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optical axis.
Proceedings of The International Astronomical Union, Aug 14, 2007
The next generation (post-VLTI) of multi-telescope interferometric arrays operated in optical/inf... more The next generation (post-VLTI) of multi-telescope interferometric arrays operated in optical/infrared wavelengths should be kilometric, from 1 to 10 km. The Concordia station offers a unique opportunity to set such an interferometer in the best atmospheric conditions presently known on Earth.
With the advent of imaging aperture-synthesis spectro-interferometers the search of exoplanetary ... more With the advent of imaging aperture-synthesis spectro-interferometers the search of exoplanetary systems appears within reach of direct detection both from the ground and space as soon as the array are co-phased.
The characteristics of the PSF at the common focus at such arrays is highly dependent on the geometry and the recombination scheme considered for the array. The IRAN recombination, Interferometric Remapped Array Nulling, has been proposed as an alternative to the Fizeau recombination. IRAN keeps intact the high resolution of the entire array given by its longest baseline. And when compared to the Fizeau recombination, IRAN provides a PSF with a much sharper central peak, surrounded by a clean field where direct imaging is possible. I set a laboratory test bench at the H. Fizeau laboratory aiming at validating its concept. The basics of IRAN are recalled in this manuscript followed by the SPIE paper where the experimental results are presented.
In order to improve even further the dynamic range of the PSFs , I propose two conceptual coronagraphic studies, both based on the AIC, Achromatic Interferential Coronagraph of J. Gay and Y. Rabbia. The first concept, also proposed by J. Gay is called CIAXE. It is a reconfiguration of the AIC into a compact and fully axial coronagraph. The motivation behind this reconfiguration it to facilitate the insertion of the coronagraph at the focus of telescopes. The CIAXE main feature consists of using two thick lenses machined in the same optical material separated by a thin air gap acting exactly like a beamsplitter. In this manuscript I recall the basics of the CIAXE and present the experimental results of the test bench I ran in Grasse. I describe, in the context of matrix optics, the derivation of the different surface radii, as well as the method conceived and used to determine the thickness difference between the lenses.
The second concept, APIC, Absolute Position Interfero-Coronagraph. Even though firstly conceived as a modification of the AIC where the 180$^o$ ambiguity is removed, APIC turned out to be a versatile coronagraph in terms of IWA and residual stellar energy. The optic behind this characteristic is cylindrical lens doublet. Apart from inducing achromatic phase shifts at its focus crossing, a cylindrical lens doublet reflects the wave front around the axis of the doublet. Depending on the orientation we give to this axis, an off-axis source's position in the image plan can be easily linked to the real position on the sky. A detailed study of the concept is presented here in the formalism of Fourier optics. The experimental results delivered by the test bench I set at ESO are also presented. They show high fidelity to the theoretical expectations. The versatility of APIC is highlighted through the study of the impact of the doublet's orientation on the IWA of the coronagraph, the intensity distribution of an on axis source and the calibration of its residual energy in the image plane.
Résumé:
Les interféromètres de seconde génération qui avec leur bases pensées à l'échelle kilométrique ouvriront la voie à l'imagerie astronomique à très haute résolution angulaire. Dans cette perspective, il faut commencer par l’étude et l’optimisation de la recombinaison de faisceaux. L’interféromètre KEOPS, Kiloparsec Explorer for Optical Planet Search, fait partie de ces projets ambitieux destinés à permettre l'imagerie à haute résolution angulaire et haute dynamique. La méthode de recombinaison de faisceaux que l’on désire retenir pour KEOPS est IRAN ou Interferometric Remapped Array Nulling. Elle permettra d’exploiter ce large réseau de télescopes en mode imagerie directe à haute résolution angulaire. Je rappelle le principe d'IRAN dans ce manuscrit et je présente les résultats, qui restent perfectible, du montage expérimental.
En termes de haute dynamique je propose deux solutions coronographiques toutes les deux basées sur le principe du CIA, Coronographe Interférentiel Achromatique de J. Gay. Le premier principe est aujourd'hui publié sur le nom d'APIC: ABSOLUTE POSITION INTERFERO-CORONAGRAPH. Si dans la configuration du CIA c'est un oeil de chat qui assure le déphasage et la rotation du champ, dans la configuration d'APIC j'ai opté pour l'utilisation de doublets de lentilles cylindriques. En variant l'orientation des doublets, d'une part, les positions des sous-images dans le plan focal final peuvent être modifiées, l'ambiguïté du CIA se retrouve ainsi supprimée et d'autre part, IWA est amélioré et l'énergie résiduelle d'une étoile dans le plan image réduite. Dans ce manuscrit je présente son principe au moyen du formalisme de Fourier. Et je présente une première étape préliminaire de sa validation expérimentale. L'autre concept coronographique est le CIAXE pour CIA dans l'aXE. C'est l’équipe conceptrice même du CIA qui a pensé à modifier le montage optique de ce dernier afin de faciliter son insertion au foyer de télescopes. Dans ce manuscrit je rappel son principe de fonctionnement en m'appuyant sur l'optique matricielle et je présente les résultats d'une expérience de laboratoire visant à l'identification des points critiques d'un tel montage afin de pouvoir tirer des conclusions pour une version opérationnelle au foyer d'un télescope.
Uploads
Papers by Fatme Allouche
Aims: We present a modified version of the AIC not only permitting these faint companions to be detected but also their relative position to be determined with respect to the parent star, a problem that was not solved in the original design of the AIC.
Methods: In our modified design, two cylindrical lens doublets were used to remove the 180° ambiguity introduced by the AIC's original design.
Results: Our theoretical study and the numerical computations show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optical axis.
The characteristics of the PSF at the common focus at such arrays is highly dependent on the geometry and the recombination scheme considered for the array. The IRAN recombination, Interferometric Remapped Array Nulling, has been proposed as an alternative to the Fizeau recombination. IRAN keeps intact the high resolution of the entire array given by its longest baseline. And when compared to the Fizeau recombination, IRAN provides a PSF with a much sharper central peak, surrounded by a clean field where direct imaging is possible. I set a laboratory test bench at the H. Fizeau laboratory aiming at validating its concept. The basics of IRAN are recalled in this manuscript followed by the SPIE paper where the experimental results are presented.
In order to improve even further the dynamic range of the PSFs , I propose two conceptual coronagraphic studies, both based on the AIC, Achromatic Interferential Coronagraph of J. Gay and Y. Rabbia. The first concept, also proposed by J. Gay is called CIAXE. It is a reconfiguration of the AIC into a compact and fully axial coronagraph. The motivation behind this reconfiguration it to facilitate the insertion of the coronagraph at the focus of telescopes. The CIAXE main feature consists of using two thick lenses machined in the same optical material separated by a thin air gap acting exactly like a beamsplitter. In this manuscript I recall the basics of the CIAXE and present the experimental results of the test bench I ran in Grasse. I describe, in the context of matrix optics, the derivation of the different surface radii, as well as the method conceived and used to determine the thickness difference between the lenses.
The second concept, APIC, Absolute Position Interfero-Coronagraph. Even though firstly conceived as a modification of the AIC where the 180$^o$ ambiguity is removed, APIC turned out to be a versatile coronagraph in terms of IWA and residual stellar energy. The optic behind this characteristic is cylindrical lens doublet. Apart from inducing achromatic phase shifts at its focus crossing, a cylindrical lens doublet reflects the wave front around the axis of the doublet. Depending on the orientation we give to this axis, an off-axis source's position in the image plan can be easily linked to the real position on the sky. A detailed study of the concept is presented here in the formalism of Fourier optics. The experimental results delivered by the test bench I set at ESO are also presented. They show high fidelity to the theoretical expectations. The versatility of APIC is highlighted through the study of the impact of the doublet's orientation on the IWA of the coronagraph, the intensity distribution of an on axis source and the calibration of its residual energy in the image plane.
Résumé:
Les interféromètres de seconde génération qui avec leur bases pensées à l'échelle kilométrique ouvriront la voie à l'imagerie astronomique à très haute résolution angulaire. Dans cette perspective, il faut commencer par l’étude et l’optimisation de la recombinaison de faisceaux. L’interféromètre KEOPS, Kiloparsec Explorer for Optical Planet Search, fait partie de ces projets ambitieux destinés à permettre l'imagerie à haute résolution angulaire et haute dynamique. La méthode de recombinaison de faisceaux que l’on désire retenir pour KEOPS est IRAN ou Interferometric Remapped Array Nulling. Elle permettra d’exploiter ce large réseau de télescopes en mode imagerie directe à haute résolution angulaire. Je rappelle le principe d'IRAN dans ce manuscrit et je présente les résultats, qui restent perfectible, du montage expérimental.
En termes de haute dynamique je propose deux solutions coronographiques toutes les deux basées sur le principe du CIA, Coronographe Interférentiel Achromatique de J. Gay. Le premier principe est aujourd'hui publié sur le nom d'APIC: ABSOLUTE POSITION INTERFERO-CORONAGRAPH. Si dans la configuration du CIA c'est un oeil de chat qui assure le déphasage et la rotation du champ, dans la configuration d'APIC j'ai opté pour l'utilisation de doublets de lentilles cylindriques. En variant l'orientation des doublets, d'une part, les positions des sous-images dans le plan focal final peuvent être modifiées, l'ambiguïté du CIA se retrouve ainsi supprimée et d'autre part, IWA est amélioré et l'énergie résiduelle d'une étoile dans le plan image réduite. Dans ce manuscrit je présente son principe au moyen du formalisme de Fourier. Et je présente une première étape préliminaire de sa validation expérimentale. L'autre concept coronographique est le CIAXE pour CIA dans l'aXE. C'est l’équipe conceptrice même du CIA qui a pensé à modifier le montage optique de ce dernier afin de faciliter son insertion au foyer de télescopes. Dans ce manuscrit je rappel son principe de fonctionnement en m'appuyant sur l'optique matricielle et je présente les résultats d'une expérience de laboratoire visant à l'identification des points critiques d'un tel montage afin de pouvoir tirer des conclusions pour une version opérationnelle au foyer d'un télescope.
Aims: We present a modified version of the AIC not only permitting these faint companions to be detected but also their relative position to be determined with respect to the parent star, a problem that was not solved in the original design of the AIC.
Methods: In our modified design, two cylindrical lens doublets were used to remove the 180° ambiguity introduced by the AIC's original design.
Results: Our theoretical study and the numerical computations show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optical axis.
The characteristics of the PSF at the common focus at such arrays is highly dependent on the geometry and the recombination scheme considered for the array. The IRAN recombination, Interferometric Remapped Array Nulling, has been proposed as an alternative to the Fizeau recombination. IRAN keeps intact the high resolution of the entire array given by its longest baseline. And when compared to the Fizeau recombination, IRAN provides a PSF with a much sharper central peak, surrounded by a clean field where direct imaging is possible. I set a laboratory test bench at the H. Fizeau laboratory aiming at validating its concept. The basics of IRAN are recalled in this manuscript followed by the SPIE paper where the experimental results are presented.
In order to improve even further the dynamic range of the PSFs , I propose two conceptual coronagraphic studies, both based on the AIC, Achromatic Interferential Coronagraph of J. Gay and Y. Rabbia. The first concept, also proposed by J. Gay is called CIAXE. It is a reconfiguration of the AIC into a compact and fully axial coronagraph. The motivation behind this reconfiguration it to facilitate the insertion of the coronagraph at the focus of telescopes. The CIAXE main feature consists of using two thick lenses machined in the same optical material separated by a thin air gap acting exactly like a beamsplitter. In this manuscript I recall the basics of the CIAXE and present the experimental results of the test bench I ran in Grasse. I describe, in the context of matrix optics, the derivation of the different surface radii, as well as the method conceived and used to determine the thickness difference between the lenses.
The second concept, APIC, Absolute Position Interfero-Coronagraph. Even though firstly conceived as a modification of the AIC where the 180$^o$ ambiguity is removed, APIC turned out to be a versatile coronagraph in terms of IWA and residual stellar energy. The optic behind this characteristic is cylindrical lens doublet. Apart from inducing achromatic phase shifts at its focus crossing, a cylindrical lens doublet reflects the wave front around the axis of the doublet. Depending on the orientation we give to this axis, an off-axis source's position in the image plan can be easily linked to the real position on the sky. A detailed study of the concept is presented here in the formalism of Fourier optics. The experimental results delivered by the test bench I set at ESO are also presented. They show high fidelity to the theoretical expectations. The versatility of APIC is highlighted through the study of the impact of the doublet's orientation on the IWA of the coronagraph, the intensity distribution of an on axis source and the calibration of its residual energy in the image plane.
Résumé:
Les interféromètres de seconde génération qui avec leur bases pensées à l'échelle kilométrique ouvriront la voie à l'imagerie astronomique à très haute résolution angulaire. Dans cette perspective, il faut commencer par l’étude et l’optimisation de la recombinaison de faisceaux. L’interféromètre KEOPS, Kiloparsec Explorer for Optical Planet Search, fait partie de ces projets ambitieux destinés à permettre l'imagerie à haute résolution angulaire et haute dynamique. La méthode de recombinaison de faisceaux que l’on désire retenir pour KEOPS est IRAN ou Interferometric Remapped Array Nulling. Elle permettra d’exploiter ce large réseau de télescopes en mode imagerie directe à haute résolution angulaire. Je rappelle le principe d'IRAN dans ce manuscrit et je présente les résultats, qui restent perfectible, du montage expérimental.
En termes de haute dynamique je propose deux solutions coronographiques toutes les deux basées sur le principe du CIA, Coronographe Interférentiel Achromatique de J. Gay. Le premier principe est aujourd'hui publié sur le nom d'APIC: ABSOLUTE POSITION INTERFERO-CORONAGRAPH. Si dans la configuration du CIA c'est un oeil de chat qui assure le déphasage et la rotation du champ, dans la configuration d'APIC j'ai opté pour l'utilisation de doublets de lentilles cylindriques. En variant l'orientation des doublets, d'une part, les positions des sous-images dans le plan focal final peuvent être modifiées, l'ambiguïté du CIA se retrouve ainsi supprimée et d'autre part, IWA est amélioré et l'énergie résiduelle d'une étoile dans le plan image réduite. Dans ce manuscrit je présente son principe au moyen du formalisme de Fourier. Et je présente une première étape préliminaire de sa validation expérimentale. L'autre concept coronographique est le CIAXE pour CIA dans l'aXE. C'est l’équipe conceptrice même du CIA qui a pensé à modifier le montage optique de ce dernier afin de faciliter son insertion au foyer de télescopes. Dans ce manuscrit je rappel son principe de fonctionnement en m'appuyant sur l'optique matricielle et je présente les résultats d'une expérience de laboratoire visant à l'identification des points critiques d'un tel montage afin de pouvoir tirer des conclusions pour une version opérationnelle au foyer d'un télescope.