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ABSTRACT The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and Redshifts (SuMIRe) project for Subaru telescope consists in four identical spectrographs feed by 600 fibers each. Each spectrograph is composed by an... more
ABSTRACT The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and Redshifts (SuMIRe) project for Subaru telescope consists in four identical spectrographs feed by 600 fibers each. Each spectrograph is composed by an optical entrance unit that creates a collimated beam and distributes the light to three channels, two visible and one near infrared. We present here the integration process of the first spectrograph channel. The verification requirements, the specific integration requirements and the product tree are the main drivers from the top plan for the Assembly Integration and Test (AIT) development process. We then present the AIT flow-down, the details for the AIT processes as well as opto-mechanical alignment procedures and tests setup. In parallel, we are developing and validating dedicated tools to secure and facilitate the AIT activities, as we have to assemble eight visible cameras, integrate and align four fiber slits, integrate and align the components of four spectrographs.
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In this paper, we describe a newly installed tomography diagnostic on the linear magnetized plasma device Mistral. The diagnostic is composed of 128 lines of sight covering a 20 cm diameter section and an acquisition rate up to 1 MHz. The... more
In this paper, we describe a newly installed tomography diagnostic on the linear magnetized plasma device Mistral. The diagnostic is composed of 128 lines of sight covering a 20 cm diameter section and an acquisition rate up to 1 MHz. The measurements are done in the visible spectrum using silicon photomultiplier arrays that require a lower amplification voltage than photomultiplier tubes for similar gains and have a fast response. Tomographic reconstruction of a rotating plasma mode is shown to illustrate the capabilities of the diagnostic.
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In this paper, we describe a newly installed tomography diagnostic on the linear magnetized plasma device Mistral. The diagnostic is composed of 128 lines of sight covering a 20 cm diameter section and an acquisition rate up to 1 MHz. The... more
In this paper, we describe a newly installed tomography diagnostic on the linear magnetized plasma device Mistral. The diagnostic is composed of 128 lines of sight covering a 20 cm diameter section and an acquisition rate up to 1 MHz. The measurements are done in the visible spectrum using silicon photomultiplier arrays that require a lower amplification voltage than photomultiplier tubes for similar gains and have a fast response. Tomographic reconstruction of a rotating plasma mode is shown to illustrate the capabilities of the diagnostic.
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POINTS is a dual astrometric optical interferometer with nominal baseline length of 2 m and measurement accuracy of 5 microarcsecs for targets separated by about 90 degrees on the sky. If selected as the ASEPS-1 mission, it could perform... more
POINTS is a dual astrometric optical interferometer with nominal baseline length of 2 m and measurement accuracy of 5 microarcsecs for targets separated by about 90 degrees on the sky. If selected as the ASEPS-1 mission, it could perform a definite search for extra-solar planetary systems, either finding and characterizing a large number of them or showing that they are far less numerous than now believed. If selected as AIM, it could be a powerful new multidisciplinary research tool, opening new areas of astrophysical research and changing the nature of the ...
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The Prime Focus Spectrograph (PFS) is an optical/near-infrared multi-fiber spectrograph with 2394 science fibers, which are distributed in 1.3 degree diameter field of view at Subaru 8.2-meter telescope. The simultaneous wide wavelength... more
The Prime Focus Spectrograph (PFS) is an optical/near-infrared multi-fiber spectrograph with 2394 science fibers, which are distributed in 1.3 degree diameter field of view at Subaru 8.2-meter telescope. The simultaneous wide wavelength coverage from 0.38 um to 1.26 um, with the resolving power of 3000, strengthens its ability to target three main survey programs: cosmology, Galactic archaeology, and galaxy/AGN evolution. A medium resolution mode with resolving power of 5000 for 0.71 um to 0.89 um also will be available by simply exchanging dispersers. PFS takes the role for the spectroscopic part of the Subaru Measurement of Images and Redshifts project, while Hyper Suprime-Cam works on the imaging part. To transform the telescope plus WFC focal ratio, a 3-mm thick broad-band coated glass-molded microlens is glued to each fiber tip. A higher transmission fiber is selected for the longest part of cable system, while one with a better FRD performance is selected for the fiber-positio...
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Depuis Helmholtz, le fonctionnement des instruments entretenus est represente par un systeme boucle faisant apparaitre un bloc excitateur et un bloc resonateur. Dans le cas de la clarinette etudiee ici, l'excitateur designe... more
Depuis Helmholtz, le fonctionnement des instruments entretenus est represente par un systeme boucle faisant apparaitre un bloc excitateur et un bloc resonateur. Dans le cas de la clarinette etudiee ici, l'excitateur designe l'anche modulant le debit d'air entrant et le resonateur le corps de l'instrument. Si cette representation est communement admise, se pose la question de la separabilite de ces deux blocs et de l'observabilite des grandeurs physiques qui les lient. Dans le cadre de l'etude du seuil d'oscillation, nous inspectons la validite de cette representation independamment de toute modelisation des blocs : les seuils mesures sont compares avec ceux obtenus par la theorie des oscillateurs dans laquelle sont introduites les valeurs experimentales des parametres du modele. Les pressions de seuil et les frequences emergentes obtenues en (3) et (4) sont comparees. L'interpretation des differences fait intervenir les difficultes d'acceder exact...
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In a previous work, results of laboratory scale measurements of long-range, across-slope propagation of broadband pulses in a shallow-water wedge-shaped oceanic waveguide with a sandy bottom were reported and analyzed [A. Korakas, F.... more
In a previous work, results of laboratory scale measurements of long-range, across-slope propagation of broadband pulses in a shallow-water wedge-shaped oceanic waveguide with a sandy bottom were reported and analyzed [A. Korakas, F. Sturm, J.-P. Sessarego, and D. Ferrand, Proceedings of the 9th ECUA (Paris, France, 29 June-4 July 2008)]. The experiments were conducted at the LMA-CNRS laboratory in Marseille (France). Strong 3D effects like mode shadow zones and multiple mode arrivals were observed, in agreement with theoretical predictions. In the present work, we focus on the frequency dependence of the received signals along the cross-slope direction. The recorded time series are analyzed mode-by-mode. The wave packets associated to each mode are extracted from the time series at several ranges and their spectra are examined by means of appropriate Fourier transforms. It turns out that, as we move out in range across-slope, the low frequency part of the spectral content of the mo...
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ABSTRACT SPHERE, a second-generation instrument for the VLT, is currently under performance validation before shipping to Chile. The IRDIS sub-system, an Infra-Red Dual-Imager and Spectrograph, was integrated on the SPHERE bench last... more
ABSTRACT SPHERE, a second-generation instrument for the VLT, is currently under performance validation before shipping to Chile. The IRDIS sub-system, an Infra-Red Dual-Imager and Spectrograph, was integrated on the SPHERE bench last December, and this paper tells the story of the 12 months preceding this milestone: the Assembly, integration and Tests (AIT) performed at Laboratoire d'Astrophysique de Marseille (LAM). Key points of the AIT strategy are then presented, and the successes and failures-human, technical, and managerial-of this adventure are discussed. We also report on the excellent optical quality achieved, paramount to guarantee ultimate performance of the SPHERE instrument, thanks to high-quality optical manufacture and a successfully applied alignment strategy.
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Depuis Helmholtz, le fonctionnement des instruments entretenus est représenté par un système bouclé faisant apparaître un bloc excitateur et un bloc résonateur. Dans le cas de la clarinette étudiée ici, l'excitateur désigne... more
Depuis Helmholtz, le fonctionnement des instruments entretenus est représenté par un système bouclé faisant apparaître un bloc excitateur et un bloc résonateur. Dans le cas de la clarinette étudiée ici, l'excitateur désigne l'anche modulant le débit d'air entrant et le résonateur le corps de l'instrument. Si cette représentation est communément admise, se pose la question de la séparabilité de ces deux blocs et de l'observabilité des grandeurs physiques qui les lient. Dans le cadre de l'étude du seuil d'oscillation, nous inspectons la validité de cette représentation indépendamment de toute modélisation des blocs : les seuils mesurés sont comparés avec ceux obtenus par la théorie des oscillateurs dans laquelle sont introduites les valeurs expérimentales des paramètres du modèle. Les pressions de seuil et les fréquences émergentes obtenues en (3) et (4) sont comparées. L'interprétation des différences fait intervenir les difficultés d'accéder exact...
The integration of the SPIRE BSM hardware and its controlling software used the hardware-in-the-loop dSPACE system to enable fast development of the control system and separate site development of the hardware and software. After this... more
The integration of the SPIRE BSM hardware and its controlling software used the hardware-in-the-loop dSPACE system to enable fast development of the control system and separate site development of the hardware and software. After this separate development, integration of the prototypes at one of the sites was completely successful. Similar development of the SMECm hardware is also described.
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Les instruments de musique à anche simple ont un fonctionnement non linéaire reposant sur l’entretien d’oscillations par une action continue du musicien. L’anche vibre au gré des ondes dans la colonne d'air et module l’apport... more
Les instruments de musique à anche simple ont un fonctionnement non linéaire reposant sur l’entretien d’oscillations par une action continue du musicien. L’anche vibre au gré des ondes dans la colonne d'air et module l’apport d’énergie qu’est le souffle du musicien. Le son n'existe qu'au delà d'un minimum de pression buccale dépendant des caractéristiques de l'instrument, de l'anche et de l'embouchure. Nous présentons les expériences préliminaires visant à la comparaison avec la théorie des seuils d'oscillation.
The interferometric mode of the ESO Very Large Telescope (VLT) permits coherent combination of stellar light beams collected by four telescopes with 8-m diameter and by several auxiliary telescopes of the 2-m class. While the position of... more
The interferometric mode of the ESO Very Large Telescope (VLT) permits coherent combination of stellar light beams collected by four telescopes with 8-m diameter and by several auxiliary telescopes of the 2-m class. While the position of the 8-m telescopes is fixed, auxiliary telescopes can be moved on rails, and can operate from 30 distributed on the top of the Observatory site for efficient UV coverage. Coherent beam combination can be achieved with the 8-m telescopes alone, with the auxiliary telescopes alone, or with any combination, up to eight telescopes in total. A distinct feature of the interferometric mode is the high sensitivity due to the 8-m pupil of the main telescopes which will be compensated by adaptive optics in the near-IR spectral regime. The VLT Interferometer (VLTI) part of the VLT Programme is conceived as an evolutionary program where a significant fraction of the interferometer's functionality is funded, and more capability may be added later while exper...
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The FUEGOS multi-object area spectrograph will be one of the six instruments of the first generation for the very large telescope. It will be installed on one of the Nasmyth platforms of the telescope unit 3 at the beginning of the year... more
The FUEGOS multi-object area spectrograph will be one of the six instruments of the first generation for the very large telescope. It will be installed on one of the Nasmyth platforms of the telescope unit 3 at the beginning of the year 2001. The instrument includes a multi-object fiber linked spectrograph to observe simultaneously up 80 targets and a fiber anamorphoser for two-dimensional spectroscopy of extended objects. Description of the instrument, its performances and status of the project are reported in this paper.
ABSTRACT The interferometric mode of the ESO Very Large Telescope (VLT) permits coherent combination of stellar light beams collected by four telescopes with 8-m diameter and by several auxiliary telescopes of the 2-m class. While the... more
ABSTRACT The interferometric mode of the ESO Very Large Telescope (VLT) permits coherent combination of stellar light beams collected by four telescopes with 8-m diameter and by several auxiliary telescopes of the 2-m class. While the position of the 8-m telescopes is fixed, auxiliary telescopes can be moved on rails, and can operate from 30 distributed on the top of the Observatory site for efficient UV coverage. Coherent beam combination can be achieved with the 8-m telescopes alone, with the auxiliary telescopes alone, or with any combination, up to eight telescopes in total. A distinct feature of the interferometric mode is the high sensitivity due to the 8-m pupil of the main telescopes which will be compensated by adaptive optics in the near-IR spectral regime. The VLT Interferometer (VLTI) part of the VLT Programme is conceived as an evolutionary program where a significant fraction of the interferometer's functionality is funded, and more capability may be added later while experience is gained and further funding becomes available. Major subsystems of the present baseline VLTI include: three auxiliary telescopes, three delay lines which permit combining the light from up to four telescopes, and a laboratory which contains an imaging beam combiner telescope and enough space to accommodate a number of experimental setups. This paper presents a general overview of the recent evolution of the project and its future development.
ABSTRACT This paper presents the GWA and the Compensating mechanism of the Near Infrared SpectroPhotometer (NISP) instrument of the ESA Euclid mission. The NIS instrument should perform an exposure sequence in the wave length range [0.9... more
ABSTRACT This paper presents the GWA and the Compensating mechanism of the Near Infrared SpectroPhotometer (NISP) instrument of the ESA Euclid mission. The NIS instrument should perform an exposure sequence in the wave length range [0.9 - 2.0Jum with different exposures of the same field of views with different passband grisms with two orthogonal dispersion directions and two wavelength range. These functionalities will be achieved by a mechanism supporting the optical elements: the Grism Wheel Assembly (GWA). The required positioning repeatability is in the order of few arcsec to keep the spectra aligned with the detector pixel columns/rows. The GWA will be assembled to the NISP Optomechanical Assembly (NIOMA) with an operating temperature of 140K. A further mechanism is necessary to compensate the torque perturbances induced by the two large wheels. It is based onto a stepper motor that will drive a flywheel.
The integration of the SPIRE BSM hardware and its controlling software used the hardware-in-the-loop dSPACE system to enable fast development of the control system and separate site development of the hardware and software. After this... more
The integration of the SPIRE BSM hardware and its controlling software used the hardware-in-the-loop dSPACE system to enable fast development of the control system and separate site development of the hardware and software. After this separate development, integration of the prototypes at one of the sites was completely successful. Similar development of the SMECm hardware is also described.
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» View Full Text: Acrobat PDF (16 KB) * * Note that full-text PDFs from conferences typically contain 1-3 pages of content, some or all of which might be an abstract, summary, or miscellaneous items. ... » View Full Text: Acrobat PDF (16... more
» View Full Text: Acrobat PDF (16 KB) * * Note that full-text PDFs from conferences typically contain 1-3 pages of content, some or all of which might be an abstract, summary, or miscellaneous items. ... » View Full Text: Acrobat PDF (16 KB) * Note that full-text PDFs from ...
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ABSTRACT SPHERE, a second-generation instrument for the VLT, is currently under performance validation before shipping to Chile. The IRDIS sub-system, an Infra-Red Dual-Imager and Spectrograph, was integrated on the SPHERE bench last... more
ABSTRACT SPHERE, a second-generation instrument for the VLT, is currently under performance validation before shipping to Chile. The IRDIS sub-system, an Infra-Red Dual-Imager and Spectrograph, was integrated on the SPHERE bench last December, and this paper tells the story of the 12 months preceding this milestone: the Assembly, integration and Tests (AIT) performed at Laboratoire d'Astrophysique de Marseille (LAM). Key points of the AIT strategy are then presented, and the successes and failures-human, technical, and managerial-of this adventure are discussed. We also report on the excellent optical quality achieved, paramount to guarantee ultimate performance of the SPHERE instrument, thanks to high-quality optical manufacture and a successfully applied alignment strategy.
ABSTRACT The interferometric mode of the ESO very large telescope (VLT) permits coherent combination of stellar light beams collected by four telescopes with 8 m diameter and by several auxiliary telescopes of the 2 m class. While the... more
ABSTRACT The interferometric mode of the ESO very large telescope (VLT) permits coherent combination of stellar light beams collected by four telescopes with 8 m diameter and by several auxiliary telescopes of the 2 m class. While the position of the 8 m telescopes is fixed, auxiliary telescopes can be moved on rails, and can operate from 30 stations distributed on the top of the observatory site for efficient UV coverage. Coherent beam combination can be achieved with the 8 m telescopes alone, with the auxiliary telescopes alone, or with any combination, up to eight telescopes in total. A distinct feature of the interferometric mode is the high sensitivity due to the 8 m pupil of the main telescopes, with the potential for adaptive optics compensation in the near- infrared spectral regime. The VLT interferometer is conceived as an evolutionary program where a significant fraction of the interferometer's functionality is initially funded, and more capability may be added later while experience is gained and further funding becomes available. The scientific program is now defined by a team which consists of a VLTI scientist at ESO and fifteen astronomers from the VLT community. ESO has recently decided to resume the construction of the VLTI which was delayed in December 1993, in order to achieve first interferometric fringes with two of the 8 m telescopes around the year 2000, and routine operation with 2 m auxiliary telescopes from 2003 onwards. This paper presents an overview of the recent evolution of the project and its future development.
Single reed instruments like clarinet and saxophone may be considered as the coupling of an acoustic resonator (the bore of the instrument) and the reed which acts as a valve modulating the air flow blown by the musician. The blowing... more
Single reed instruments like clarinet and saxophone may be considered as the coupling of an acoustic resonator (the bore of the instrument) and the reed which acts as a valve modulating the air flow blown by the musician. The blowing pressure required for sound emergence is mainly determined by the acoustic characteristics of the bore. However previous studies explain that it may be largely influenced by the way the player controls the dynamical behaviour of the reed, in particular how the player's lips damp the mechanical resonance of the reed. We will present preliminary experimental work in order to compare the measurements with the pressure threshold theory.
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HAL - hal.archives-ouvertes.fr, CCSd - Centre pour la Communication Scientifique Direct. Accueil; Dépôt: S'authentifier; S'inscrire. Consultation: Par domaine; Les 30 derniers dépôts; Par année de publication, rédaction, dépôt;... more
HAL - hal.archives-ouvertes.fr, CCSd - Centre pour la Communication Scientifique Direct. Accueil; Dépôt: S'authentifier; S'inscrire. Consultation: Par domaine; Les 30 derniers dépôts; Par année de publication, rédaction, dépôt; Par type de publication; Par collection; Les portails de l'archive ouverte HAL; Par établissement (extraction automatique); ArXiv; Les Thèses (TEL). Recherche: Recherche simple; Recherche avancée; Accès par identifiant; Les Thèses ...
HAL - hal.archives-ouvertes.fr, CCSd - Centre pour la Communication Scientifique Direct. Accueil; Dépôt: S'authentifier; S'inscrire. Consultation: Par domaine; Les 30 derniers dépôts; Par année de publication, rédaction, dépôt;... more
HAL - hal.archives-ouvertes.fr, CCSd - Centre pour la Communication Scientifique Direct. Accueil; Dépôt: S'authentifier; S'inscrire. Consultation: Par domaine; Les 30 derniers dépôts; Par année de publication, rédaction, dépôt; Par type de publication; Par collection; Les portails de l'archive ouverte HAL; Par établissement (extraction automatique); ArXiv; Les Thèses (TEL). Recherche: Recherche simple; Recherche avancée; Accès par identifiant; Les Thèses ...
HAL - hal.archives-ouvertes.fr, CCSd - Centre pour la Communication Scientifique Direct. Accueil; Dépôt: S'authentifier; S'inscrire. Consultation: Par domaine; Les 30 derniers dépôts; Par année de publication, rédaction, dépôt;... more
HAL - hal.archives-ouvertes.fr, CCSd - Centre pour la Communication Scientifique Direct. Accueil; Dépôt: S'authentifier; S'inscrire. Consultation: Par domaine; Les 30 derniers dépôts; Par année de publication, rédaction, dépôt; Par type de publication; Par collection; Les portails de l'archive ouverte HAL; Par établissement (extraction automatique); ArXiv; Les Thèses (TEL). Recherche: Recherche simple; Recherche avancée; Accès par identifiant; Les Thèses ...