ABSTRACT The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and Redshifts (Su... 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.
In this paper, we describe a newly installed tomography diagnostic on the linear magnetized plasm... 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.
In this paper, we describe a newly installed tomography diagnostic on the linear magnetized plasm... 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.
POINTS is a dual astrometric optical interferometer with nominal baseline length of 2 m and measu... 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 ...
The Prime Focus Spectrograph (PFS) is an optical/near-infrared multi-fiber spectrograph with 2394... 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...
Depuis Helmholtz, le fonctionnement des instruments entretenus est represente par un systeme bouc... 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...
In a previous work, results of laboratory scale measurements of long-range, across-slope propagat... 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...
Ground-based and Airborne Instrumentation for Astronomy IV, 2012
ABSTRACT SPHERE, a second-generation instrument for the VLT, is currently under performance valid... 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 Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and Redshifts (Su... 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.
In this paper, we describe a newly installed tomography diagnostic on the linear magnetized plasm... 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.
In this paper, we describe a newly installed tomography diagnostic on the linear magnetized plasm... 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.
POINTS is a dual astrometric optical interferometer with nominal baseline length of 2 m and measu... 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 ...
The Prime Focus Spectrograph (PFS) is an optical/near-infrared multi-fiber spectrograph with 2394... 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...
Depuis Helmholtz, le fonctionnement des instruments entretenus est represente par un systeme bouc... 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...
In a previous work, results of laboratory scale measurements of long-range, across-slope propagat... 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...
Ground-based and Airborne Instrumentation for Astronomy IV, 2012
ABSTRACT SPHERE, a second-generation instrument for the VLT, is currently under performance valid... 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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Papers by Didier Ferrand