Adaptive optics provides a real-time compensation for atmospheric turbulence that severely limits... more Adaptive optics provides a real-time compensation for atmospheric turbulence that severely limits the resolution of ground-based observation systems. The correction quality relies on a key component, that is, the wavefront sensor (WFS). When observing extended sources, WFS precision is limited by anisoplanatism effects. Anisoplanatism induces a variation of the turbulent phase and of the collected flux in the field of view. We study the effect of this phase and scintillation anisoplanatism on wavefront analysis. An analytical expression of the error induced is given in the Rytov regime. The formalism is applied to a solar and an endoatmospheric observation. Scintillation effects are generally disregarded, especially in astronomical conditions. We shall prove that this approximation is not valid with extended objects.
Cn2 profile monitoring usually makes use of wavefront slope correlations or of scintillation patt... more Cn2 profile monitoring usually makes use of wavefront slope correlations or of scintillation pattern correlations. Wavefront slope correlations provide sensitivity to layers close to the receiving plane. In addition, scintillation correlations allow a better sensitivity to high turbulence layers. Wavefront slope and scintillation correlations are therefore complementary. Slopes and scintillation being recorded simultaneously with a Shack-Hartmann wavefront sensor (SHWFS), we propose here to exploit their correlation to retrieve the Cn2 profile. The measurement method named COupled SLodar scIDAR (CO-SLIDAR) uses correlations of SHWFS data from two separated stars. A maximum-likelihood method is developed to estimate precisely the positions and intensities corresponding to each SHWFS spot, which are used as inputs for CO-SLIDAR. First results are presented using SHWFS real data from a binary star.
ABSTRACT A submillimeter balloon-borne receiver, including a 380 GHz cryogenic Schottky diode mix... more ABSTRACT A submillimeter balloon-borne receiver, including a 380 GHz cryogenic Schottky diode mixer with 6 GHz IF, has been investigated. At room temperature, 1400K DSB mixer noise temperature has been achieved; cooling down the device should allow a strong increase in receiver sensitivity.
The superheterodyne detection technique used for the spectrometer instrument of the PRONAOS proje... more The superheterodyne detection technique used for the spectrometer instrument of the PRONAOS project will provide a very high spectral resolution (delta nu/nu = 10-6). The most critical components are those located at the front-end of the receiver: their contribution dominates the total noise of the receiver. Therefore, it is important to perform accurate studies for specific components, such as mixers and multipliers working in the submillimeter wave range. Difficulties in generating enough local oscillator (LO) power at high frequencies make SIS mixers very desirable for operation above 300 GHz. The low LO power requirements and the low noise temperature of these mixers are the primary reason for building an SIS receiver. This paper reports the successful fabrication of small (less than or equal to 1 sq micron) Nb/Al-O(x)/Nb junctions and arrays with excellent I-V characteristics and very good reliability, resulting in a low noise receiver performance measured in the 368/380 GHz fr...
A balloon-borne observatory (PRONAOS) including a two meter telescope associated with a submillim... more A balloon-borne observatory (PRONAOS) including a two meter telescope associated with a submillimeter heterodyne spectrometer for radioastronomy is supported by the French space agency (CNES) to prepare the future space programs in astrophysics. This instrument will be used to simultaneously detect the 368 GHz O(subscript 2) and the 380 GHz H(subscript 2)O lines in the interstellar medium. Observations in this
ABSTRACT The design phase for the Wide Field Adaptive Optics (WFAO) systems for the ELTs has star... more ABSTRACT The design phase for the Wide Field Adaptive Optics (WFAO) systems for the ELTs has started. LTAO (ATLAS), MCAO (MAORY) and MOAO (EAGLE) approaches have been studied for the E-ELT. All these systems have in common a need for a precise tomographic reconstruction of the turbulent volume. In that frame, the Cn2 structure, representing the turbulence strength, becomes a critical parameter for the final tomographic reconstruction performance. Getting of high-resolution Cn2 profiles is then a crucial point for the design of E-ELT AO systems. In this context, we have proposed a new profilometry method using Shack-Hartmann (SH) data. Slopes and scintillation indexes being recorded simultaneously with a Shack-Hartmann wavefront sensor (SHWFS), their correlation is exploited in order to retrieve the Cn2 profile. This method, named CO-SLIDAR (COupled Slope and scIntillation Detection And Ranging), uses correlation of SHWFS data from two separated stars. CO-SLIDAR has been validated in numerical simulations in a precedent work. The next step is an on-sky validation with a full-dedicated SHWFS, to measure a Cn2 profile with 40 layers, up to 20 km of altitude, with a 500m altitude resolution. The system will be set up on a 1.5m telescope. Here, we first expound the theoretical background of SH data and CO-SLIDAR processing. The Cn2 profile is estimated by minimizing a maximum likelihood criterion under positivity constraint. Then, we describe the experimental system and the future on-sky experiment. Determination of outer scale L0 with CO-SLIDAR, taking advantage of the large telescope diameter, is investigated.
COupled SLope and scIntillation Detection And Ranging (CO-SLIDAR) is a recent profiling method of... more COupled SLope and scIntillation Detection And Ranging (CO-SLIDAR) is a recent profiling method of the vertical distribution of atmospheric turbulence strength (C 2 n profile). It takes advantage of correlations of slopes and of scintillation, both measured with a Shack-Hartmann wavefront sensor on a binary star. In this paper, we present the improved CO-SLIDAR reconstruction method of the C 2 n profile and the first on-sky results of the CO-SLIDAR profiler. We examine CO-SLIDAR latest performance in simulation, taking into account the detection noise bias and estimating error bars along with the turbulence profile. The estimated C 2 n profiles demonstrate the accuracy of the CO-SLIDAR method, showing sensitivity to both low and high altitude turbulent layers. CO-SLIDAR is tested on-sky for the first time, on the 1.5 m MeO (Métrologie Optique) telescope at Observatoire de la Côte d'Azur (France). The reconstructed profiles are compared to turbulence profiles estimated from meteorological data and a good agreement is found. We discuss CO-SLIDAR's contribution in the C 2 n profilers' landscape and we propose some improvements of the instrument.
All Wide Field Adaptive Optics systems for the ELTs need a precise tomographic reconstruction of ... more All Wide Field Adaptive Optics systems for the ELTs need a precise tomographic reconstruction of the turbulent volume. The Cn2 profile, representing the turbulence strength, becomes a critical parameter for the tomographic reconstruction performance. CO-SLIDAR (Coupled Slope and scIntillation Detection And Ranging) is a method using both correlations of slopes and correlations of scintillation recorded with a Shack-Hartmann on binary stars. The extent of the method to a single source is also possible. CO-SLIDAR leads to a precise retrieval of the Cn2 profile for both low and high altitude layers. Here, we present the first on-sky results of the method. A Shack-Hartmann with 30x30 subapertures is set up on a 1.5-meter telescope. Images are recorded on single and binary stars. Preliminary data reductions are performed to check the hypothesis of Kolmogorov turbulence and estimate the Fried parameter. We also control the hypothesis of Rytov regime. We finally restore the Cn2 profiles. T...
Deconvolution from wavefront sensing is a powerful and low cost high resolution imaging technique... more Deconvolution from wavefront sensing is a powerful and low cost high resolution imaging technique designed to compensate for the image degradation due to atmospheric turbulence. It is based on a simultaneous recording of shift exposure images and wavefront sensor (WFS) data. To date, the data processing consists of a sequential estimation of the wavefronts given the WFS data and then
Scintillation effects caused by the fluctuations of the refractive index of air are not negligibl... more Scintillation effects caused by the fluctuations of the refractive index of air are not negligible in the stratosphere. Recent experiments highlight the composite nature of optical turbulence in the stratosphere. We present an analytical model of scintillation based on a 3-D model of anisotropic and isotropic refractive index fluctuations spectrum that predicts scintillation rates inside the Rytov regime. This model
EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installe... more EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installed at the Gravity Invariant Focal Station of the E-ELT, covering a field of view of 50 square arcminutes. Its main scientific drivers are the physics and evolution of high-redshift ...
1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, 2010
1 Centre for Advanced Instrumentation, Durham University, South Road, Durham, DH1 3LE, UK 2 Obser... more 1 Centre for Advanced Instrumentation, Durham University, South Road, Durham, DH1 3LE, UK 2 Observatoire de Paris, Place Jules Janssen, F-92 195 Meudon Cedex, France 3 UKATC, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK 4 ...
EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installe... more EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installed at the Gravity Invariant Focal Station of the E-ELT, covering a field of view of 50 square arcminutes. Its main scientific drivers are the physics and evolution of high-redshift galaxies, the detection and characterization of first-light objects and the physics of galaxy evolution from stellar
1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, 2010
... 1 INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy 2 Office Na... more ... 1 INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy 2 Office National d'Etudes et de Recherches Aerospatiales, BP 72, 92322 Châtillon cedex, France 3 Università di Bologna - Dipartimento di Astronomia, via Ranzani 1, 40127 Bologna, Italy 4 ...
EAGLE is the multi-object spatially-resolved near-IR spectrograph instrument concept for the E-EL... more EAGLE is the multi-object spatially-resolved near-IR spectrograph instrument concept for the E-ELT, relying on a distributed Adaptive Optics, so-called Multi Object Adaptive Optics. This paper presents the results of a phase A study. Using 84×84 actuator deformable mirrors, the performed analysis demonstrates that 6 laser guide stars (on an outer ring of 7.2' diameter) and up to 5 natural guide stars of magnitude R < 17, picked-up in a 7.3' diameter patrol field of view, allow us to obtain an overall performance in terms of Ensquared Energy of 35% in a 75×75mas2 resolution element at H band whatever the target direction in the centred 5' science field for median seeing conditions. In terms of sky coverage, the probability to find the 5 natural guide stars is close to 90% at galactic latitudes |b| ~ 60 deg. Several MOAO demonstration activities are also on-going.
The Multi-conjugate Adaptive Optics RelaY (MAORY) for the European Extremely Large Telescope (E-E... more The Multi-conjugate Adaptive Optics RelaY (MAORY) for the European Extremely Large Telescope (E-ELT) provides a corrected field of view of up to 2 arcmin diameter over the wavelength range 0.8-2.4 μm. It is expected to achieve a correction of high quality and ...
1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, 2010
ATLAS is the future Laser Tomographic AO system of the E-ELT. Its goal is to provide a diffractio... more ATLAS is the future Laser Tomographic AO system of the E-ELT. Its goal is to provide a diffraction limited PSF in K band for a significant part of the sky (typically more than 60%). A first concept of the module combined with optomechanical implementation and associated performance is presented. Results show the feasibility of the concept, its versatility and a
ATLAS is a generic Laser Tomographic AO (LTAO) system for the E-ELT. Based on modular, relatively... more ATLAS is a generic Laser Tomographic AO (LTAO) system for the E-ELT. Based on modular, relatively simple, and yet innovative concepts, it aims at providing diffraction limited images in the near infra-red for a close to 100 percent sky coverage.
Ground-based and Airborne Instrumentation for Astronomy III, 2010
EAGLE is an instrument under consideration for the European Extremely Large Telescope (E-ELT). EA... more EAGLE is an instrument under consideration for the European Extremely Large Telescope (E-ELT). EAGLE will be installed at the Gravity Invariant Focal Station of the E-ELT. The baseline design consists of 20 IFUs deployable over a patrol field of ~40 arcmin2. Each IFU has an ...
Adaptive optics provides a real-time compensation for atmospheric turbulence that severely limits... more Adaptive optics provides a real-time compensation for atmospheric turbulence that severely limits the resolution of ground-based observation systems. The correction quality relies on a key component, that is, the wavefront sensor (WFS). When observing extended sources, WFS precision is limited by anisoplanatism effects. Anisoplanatism induces a variation of the turbulent phase and of the collected flux in the field of view. We study the effect of this phase and scintillation anisoplanatism on wavefront analysis. An analytical expression of the error induced is given in the Rytov regime. The formalism is applied to a solar and an endoatmospheric observation. Scintillation effects are generally disregarded, especially in astronomical conditions. We shall prove that this approximation is not valid with extended objects.
Cn2 profile monitoring usually makes use of wavefront slope correlations or of scintillation patt... more Cn2 profile monitoring usually makes use of wavefront slope correlations or of scintillation pattern correlations. Wavefront slope correlations provide sensitivity to layers close to the receiving plane. In addition, scintillation correlations allow a better sensitivity to high turbulence layers. Wavefront slope and scintillation correlations are therefore complementary. Slopes and scintillation being recorded simultaneously with a Shack-Hartmann wavefront sensor (SHWFS), we propose here to exploit their correlation to retrieve the Cn2 profile. The measurement method named COupled SLodar scIDAR (CO-SLIDAR) uses correlations of SHWFS data from two separated stars. A maximum-likelihood method is developed to estimate precisely the positions and intensities corresponding to each SHWFS spot, which are used as inputs for CO-SLIDAR. First results are presented using SHWFS real data from a binary star.
ABSTRACT A submillimeter balloon-borne receiver, including a 380 GHz cryogenic Schottky diode mix... more ABSTRACT A submillimeter balloon-borne receiver, including a 380 GHz cryogenic Schottky diode mixer with 6 GHz IF, has been investigated. At room temperature, 1400K DSB mixer noise temperature has been achieved; cooling down the device should allow a strong increase in receiver sensitivity.
The superheterodyne detection technique used for the spectrometer instrument of the PRONAOS proje... more The superheterodyne detection technique used for the spectrometer instrument of the PRONAOS project will provide a very high spectral resolution (delta nu/nu = 10-6). The most critical components are those located at the front-end of the receiver: their contribution dominates the total noise of the receiver. Therefore, it is important to perform accurate studies for specific components, such as mixers and multipliers working in the submillimeter wave range. Difficulties in generating enough local oscillator (LO) power at high frequencies make SIS mixers very desirable for operation above 300 GHz. The low LO power requirements and the low noise temperature of these mixers are the primary reason for building an SIS receiver. This paper reports the successful fabrication of small (less than or equal to 1 sq micron) Nb/Al-O(x)/Nb junctions and arrays with excellent I-V characteristics and very good reliability, resulting in a low noise receiver performance measured in the 368/380 GHz fr...
A balloon-borne observatory (PRONAOS) including a two meter telescope associated with a submillim... more A balloon-borne observatory (PRONAOS) including a two meter telescope associated with a submillimeter heterodyne spectrometer for radioastronomy is supported by the French space agency (CNES) to prepare the future space programs in astrophysics. This instrument will be used to simultaneously detect the 368 GHz O(subscript 2) and the 380 GHz H(subscript 2)O lines in the interstellar medium. Observations in this
ABSTRACT The design phase for the Wide Field Adaptive Optics (WFAO) systems for the ELTs has star... more ABSTRACT The design phase for the Wide Field Adaptive Optics (WFAO) systems for the ELTs has started. LTAO (ATLAS), MCAO (MAORY) and MOAO (EAGLE) approaches have been studied for the E-ELT. All these systems have in common a need for a precise tomographic reconstruction of the turbulent volume. In that frame, the Cn2 structure, representing the turbulence strength, becomes a critical parameter for the final tomographic reconstruction performance. Getting of high-resolution Cn2 profiles is then a crucial point for the design of E-ELT AO systems. In this context, we have proposed a new profilometry method using Shack-Hartmann (SH) data. Slopes and scintillation indexes being recorded simultaneously with a Shack-Hartmann wavefront sensor (SHWFS), their correlation is exploited in order to retrieve the Cn2 profile. This method, named CO-SLIDAR (COupled Slope and scIntillation Detection And Ranging), uses correlation of SHWFS data from two separated stars. CO-SLIDAR has been validated in numerical simulations in a precedent work. The next step is an on-sky validation with a full-dedicated SHWFS, to measure a Cn2 profile with 40 layers, up to 20 km of altitude, with a 500m altitude resolution. The system will be set up on a 1.5m telescope. Here, we first expound the theoretical background of SH data and CO-SLIDAR processing. The Cn2 profile is estimated by minimizing a maximum likelihood criterion under positivity constraint. Then, we describe the experimental system and the future on-sky experiment. Determination of outer scale L0 with CO-SLIDAR, taking advantage of the large telescope diameter, is investigated.
COupled SLope and scIntillation Detection And Ranging (CO-SLIDAR) is a recent profiling method of... more COupled SLope and scIntillation Detection And Ranging (CO-SLIDAR) is a recent profiling method of the vertical distribution of atmospheric turbulence strength (C 2 n profile). It takes advantage of correlations of slopes and of scintillation, both measured with a Shack-Hartmann wavefront sensor on a binary star. In this paper, we present the improved CO-SLIDAR reconstruction method of the C 2 n profile and the first on-sky results of the CO-SLIDAR profiler. We examine CO-SLIDAR latest performance in simulation, taking into account the detection noise bias and estimating error bars along with the turbulence profile. The estimated C 2 n profiles demonstrate the accuracy of the CO-SLIDAR method, showing sensitivity to both low and high altitude turbulent layers. CO-SLIDAR is tested on-sky for the first time, on the 1.5 m MeO (Métrologie Optique) telescope at Observatoire de la Côte d'Azur (France). The reconstructed profiles are compared to turbulence profiles estimated from meteorological data and a good agreement is found. We discuss CO-SLIDAR's contribution in the C 2 n profilers' landscape and we propose some improvements of the instrument.
All Wide Field Adaptive Optics systems for the ELTs need a precise tomographic reconstruction of ... more All Wide Field Adaptive Optics systems for the ELTs need a precise tomographic reconstruction of the turbulent volume. The Cn2 profile, representing the turbulence strength, becomes a critical parameter for the tomographic reconstruction performance. CO-SLIDAR (Coupled Slope and scIntillation Detection And Ranging) is a method using both correlations of slopes and correlations of scintillation recorded with a Shack-Hartmann on binary stars. The extent of the method to a single source is also possible. CO-SLIDAR leads to a precise retrieval of the Cn2 profile for both low and high altitude layers. Here, we present the first on-sky results of the method. A Shack-Hartmann with 30x30 subapertures is set up on a 1.5-meter telescope. Images are recorded on single and binary stars. Preliminary data reductions are performed to check the hypothesis of Kolmogorov turbulence and estimate the Fried parameter. We also control the hypothesis of Rytov regime. We finally restore the Cn2 profiles. T...
Deconvolution from wavefront sensing is a powerful and low cost high resolution imaging technique... more Deconvolution from wavefront sensing is a powerful and low cost high resolution imaging technique designed to compensate for the image degradation due to atmospheric turbulence. It is based on a simultaneous recording of shift exposure images and wavefront sensor (WFS) data. To date, the data processing consists of a sequential estimation of the wavefronts given the WFS data and then
Scintillation effects caused by the fluctuations of the refractive index of air are not negligibl... more Scintillation effects caused by the fluctuations of the refractive index of air are not negligible in the stratosphere. Recent experiments highlight the composite nature of optical turbulence in the stratosphere. We present an analytical model of scintillation based on a 3-D model of anisotropic and isotropic refractive index fluctuations spectrum that predicts scintillation rates inside the Rytov regime. This model
EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installe... more EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installed at the Gravity Invariant Focal Station of the E-ELT, covering a field of view of 50 square arcminutes. Its main scientific drivers are the physics and evolution of high-redshift ...
1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, 2010
1 Centre for Advanced Instrumentation, Durham University, South Road, Durham, DH1 3LE, UK 2 Obser... more 1 Centre for Advanced Instrumentation, Durham University, South Road, Durham, DH1 3LE, UK 2 Observatoire de Paris, Place Jules Janssen, F-92 195 Meudon Cedex, France 3 UKATC, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK 4 ...
EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installe... more EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installed at the Gravity Invariant Focal Station of the E-ELT, covering a field of view of 50 square arcminutes. Its main scientific drivers are the physics and evolution of high-redshift galaxies, the detection and characterization of first-light objects and the physics of galaxy evolution from stellar
1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, 2010
... 1 INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy 2 Office Na... more ... 1 INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy 2 Office National d&amp;#x27;Etudes et de Recherches Aerospatiales, BP 72, 92322 Châtillon cedex, France 3 Università di Bologna - Dipartimento di Astronomia, via Ranzani 1, 40127 Bologna, Italy 4 ...
EAGLE is the multi-object spatially-resolved near-IR spectrograph instrument concept for the E-EL... more EAGLE is the multi-object spatially-resolved near-IR spectrograph instrument concept for the E-ELT, relying on a distributed Adaptive Optics, so-called Multi Object Adaptive Optics. This paper presents the results of a phase A study. Using 84×84 actuator deformable mirrors, the performed analysis demonstrates that 6 laser guide stars (on an outer ring of 7.2' diameter) and up to 5 natural guide stars of magnitude R < 17, picked-up in a 7.3' diameter patrol field of view, allow us to obtain an overall performance in terms of Ensquared Energy of 35% in a 75×75mas2 resolution element at H band whatever the target direction in the centred 5' science field for median seeing conditions. In terms of sky coverage, the probability to find the 5 natural guide stars is close to 90% at galactic latitudes |b| ~ 60 deg. Several MOAO demonstration activities are also on-going.
The Multi-conjugate Adaptive Optics RelaY (MAORY) for the European Extremely Large Telescope (E-E... more The Multi-conjugate Adaptive Optics RelaY (MAORY) for the European Extremely Large Telescope (E-ELT) provides a corrected field of view of up to 2 arcmin diameter over the wavelength range 0.8-2.4 μm. It is expected to achieve a correction of high quality and ...
1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, 2010
ATLAS is the future Laser Tomographic AO system of the E-ELT. Its goal is to provide a diffractio... more ATLAS is the future Laser Tomographic AO system of the E-ELT. Its goal is to provide a diffraction limited PSF in K band for a significant part of the sky (typically more than 60%). A first concept of the module combined with optomechanical implementation and associated performance is presented. Results show the feasibility of the concept, its versatility and a
ATLAS is a generic Laser Tomographic AO (LTAO) system for the E-ELT. Based on modular, relatively... more ATLAS is a generic Laser Tomographic AO (LTAO) system for the E-ELT. Based on modular, relatively simple, and yet innovative concepts, it aims at providing diffraction limited images in the near infra-red for a close to 100 percent sky coverage.
Ground-based and Airborne Instrumentation for Astronomy III, 2010
EAGLE is an instrument under consideration for the European Extremely Large Telescope (E-ELT). EA... more EAGLE is an instrument under consideration for the European Extremely Large Telescope (E-ELT). EAGLE will be installed at the Gravity Invariant Focal Station of the E-ELT. The baseline design consists of 20 IFUs deployable over a patrol field of ~40 arcmin2. Each IFU has an ...
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