Luc Dubbeldam - Academia.edu (original) (raw)
Papers by Luc Dubbeldam
Experimental Astronomy
The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 20... more The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained.
Journal of Astronomical Telescopes, Instruments, and Systems, 2017
The soft x-ray spectrometer was designed to operate onboard the Japanese Hitomi (ASTRO-H) satelli... more The soft x-ray spectrometer was designed to operate onboard the Japanese Hitomi (ASTRO-H) satellite. In the beam of this instrument, there was a filter wheel containing x-ray filters and active calibration sources. This paper describes this filter wheel. We show the purpose of the filters and the preflight calibrations performed. In addition, we present the calibration source design and measured performance. Finally, we conclude with prospects for future missions.
SPACOMM 2011, The …, 2011
This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI), to be launched onboar... more This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI), to be launched onboard of ESA's Herschel Space Observatory, by 2008. It includes the first results from the instrument level tests. The instrument is designed to be electronically tuneable over a wide and continuous frequency range in the Far Infrared, with velocity resolutions better than 0.1 km/s with a high sensitivity. This will enable detailed investigations of a wide variety of astronomical sources, ranging from solar system objects, star formation regions to nuclei of galaxies. The instrument comprises 5 frequency bands covering 480-1150 GHz with SIS mixers and a sixth dual frequency band, for the 1410-1910 GHz range, with Hot Electron Bolometer Mixers (HEB). The Local Oscillator (LO) subsystem consists of a dedicated Ka-band synthesizer followed by 7 times 2 chains of frequency multipliers, 2 chains for each frequency band. A pair of Auto-Correlators and a pair of Acousto-Optic spectrometers process the two IF signals from the dual-polarization front-ends to provide instantaneous frequency coverage of 4 GHz, with a set of resolutions (140 kHz to 1 MHz), better than < 0.1 km/s. After a successful qualification program, the flight instrument was delivered and entered the testing phase at satellite level. We will also report on the pre-flight test and calibration results together with the expected in-flight performance.
International Conference on Space Optics — ICSO 2018, Jul 12, 2019
In this article the immersed gratings for the ESA Copernicus Sentinel-5 mission are presented. Th... more In this article the immersed gratings for the ESA Copernicus Sentinel-5 mission are presented. The manufacturing approach is shown and the optical performance of the SWIR-3 immersed gratings as well as the results of the environmental tests are discussed. The immersed gratings show an average efficiency of 60% and a wavefront error of 200 nm rms. The total integrated scatter over the complete stray-light hemisphere excluding ghosts from internal reflections is found to be 0.2% using a conservative estimate. A method for the derivation of the wavefront error from separate surface measurements is presented and the results are compared to measurements with an experimental Shack-Hartmann setup. The immersed gratings are produced by bonding a prism to a wafer with a grating. Environmental tests and testing at operational temperatures show the suitability of this approach for complex space optical components. The article concludes with possible improvements in the optical performance of future immersed gratings.
SPACOMM 2011, The …, 2011
The Heterodyne Instrument for the Far-Infrared onboard the ESA Herschel satellite is a heterodyne... more The Heterodyne Instrument for the Far-Infrared onboard the ESA Herschel satellite is a heterodyne spectrometer with unprecedented frequency range, resolution and sensibility. It is composed of two spectrometers, a Local Oscillator Unit, producing the mixing signals, a Focal Plane Unit, perfoming mixing and amplification, and an Instrument Control Unit, hosting a DSP where the On Board Software (OBS) runs. The OBS coordinates the other units, manages the interface with the spacecraft and monitors the instrument status. A synthetic description of the OBS organization and functioning is presented in this paper.
Microelectronic Engineering, Apr 1, 1988
Research was carried out on a voltage contrast detector in a scanning electron microscope. The fo... more Research was carried out on a voltage contrast detector in a scanning electron microscope. The form of the detector was investigated. Test techniques are reviewed as an introduction to the field of IC-testing. The physical background of secondary electron emission is discussed. The signal to noise ratio of voltage measurements for the spectrometer is calculated and compared with the theoretical maximum and values of conventional designs. Several voltage contrast detectors are described. The spectrometer is described and the influence of the magnetic field on the focusing properties of the primary system and the feasibility of a multiple focusing electron in a parallelizer and in the spectrometer was calculated with a ray tracing program. Experimental results are detailed.
X-ray calibration of the Electro-Optical Breadboard Model (EOBB) of the XXM Reflection Grating Sp... more X-ray calibration of the Electro-Optical Breadboard Model (EOBB) of the XXM Reflection Grating Spectrometer has been carried out at the Panter test facility in Germany. The EOBB prototype optics consisted of a four-shell grazing incidence mirror module followed by an array of eight reflection gratings. The dispersed x-rays were detected by an array of three CCDs. Line profile and efficiency
Advances in Optical and Electron Microscopy, 1991
EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy V, 1994
Space Optics 1994: Earth Observation and Astronomy, 1994
ABSTRACT The Reflection Grating Spectrometer (RGS) onboard the ESA satellite XMM (X-ray Multi Mir... more ABSTRACT The Reflection Grating Spectrometer (RGS) onboard the ESA satellite XMM (X-ray Multi Mirror mission) combines a high resolving power (approximately 400 at 0.5 keV) with a large effective area (approximately 200 cm(superscript 2)). The spectral range selected for RGS (5 - 35 angstroms) contains the K shell transitions of N, O, Ne, Mg, Al, Si and S as well as the important L shell transitions of FE. The resolving power allows the study of a wide variety of challenging scientific questions. Detailed temperature diagnostics are feasible as the ionization balance is a unique function of the distribution of the electron temperature. Density diagnostics are provided by studying He-like triplets where the ratio of the forbidden to intercombination lines varies with density. Other fields of interest include the determination of elemental abundances, the study of optical depth effects, velocity diagnostics by measuring Doppler shifts and the estimate of magnetic fields through the observation of Zeeman splitting. The resolving power is obtained by an array of 240 gratings placed behind the mirrors of the telescope, dispersing about half of the X-rays in two spectroscopic orders. The X-rays are recorded by an array of 9 large format CCDs. These CCDs are operated in the frame transfer mode. They are back illuminated as the quantum efficiency of front illuminated devices is poor at low energies because of their poly-silicon gate structure. To suppress dark current the CCDs are passively cooled. In order to obtain the effective area of about 200 cm(superscript 2), grating arrays and CCD cameras are placed behind two of the three XMM telescopes. A model of RGS was tested last autumn ('93) at the Panter long beam X-ray facility in Munich. The model consisted of a subset of four mirrors, eight representative gratings covering a small section of the inner mirror shells and a CCD camera containing three CCDs. The purpose of these tests was to verify the resolution and sensitivity of the instrument as a function of X-ray energy. Extensive simulations, using a Monte Carlo raytracing code, are used to interpret these tests. Preliminary results of these tests will be discussed and compared to the calculated response.
X-Ray Optics, Instruments, and Missions III, 2000
ABSTRACT
EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy VII, 1996
ABSTRACT The x-ray multi-mirror (XMM) mission is the second of four cornerstone projects of the E... more ABSTRACT The x-ray multi-mirror (XMM) mission is the second of four cornerstone projects of the ESA long-term program for space science, Horizon 2000. The payload comprises three co- aligned high-throughput, imaging telescopes with a FOV of 30 arcmin and spatial resolution less than 20 arcsec. Imaging CCD-detectors (EPIC) are placed in the focus of each telescope. Behind two of the three telescopes, about half the x-ray light is utilized by the reflection grating spectrometer (RGS). The x-ray instruments are co-aligned and measure simultaneously with an optical monitor (OM). The RGS instruments achieve high spectral resolution and high efficiency in the combined first and second order of diffraction in the wavelength range between 5 and 35 angstrom. The design incorporates an array of reflection gratings placed in the converging beam at the exit from the x-ray telescope. The grating stack diffracts the x-rays to an array of dedicated charge-coupled device (CCD) detectors offset from the telescope focal plane. The cooling of the CCDs is provided through a passive radiator. The design and performance of the instrument are described below.
Experimental Astronomy
The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 20... more The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained.
Journal of Astronomical Telescopes, Instruments, and Systems, 2017
The soft x-ray spectrometer was designed to operate onboard the Japanese Hitomi (ASTRO-H) satelli... more The soft x-ray spectrometer was designed to operate onboard the Japanese Hitomi (ASTRO-H) satellite. In the beam of this instrument, there was a filter wheel containing x-ray filters and active calibration sources. This paper describes this filter wheel. We show the purpose of the filters and the preflight calibrations performed. In addition, we present the calibration source design and measured performance. Finally, we conclude with prospects for future missions.
SPACOMM 2011, The …, 2011
This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI), to be launched onboar... more This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI), to be launched onboard of ESA's Herschel Space Observatory, by 2008. It includes the first results from the instrument level tests. The instrument is designed to be electronically tuneable over a wide and continuous frequency range in the Far Infrared, with velocity resolutions better than 0.1 km/s with a high sensitivity. This will enable detailed investigations of a wide variety of astronomical sources, ranging from solar system objects, star formation regions to nuclei of galaxies. The instrument comprises 5 frequency bands covering 480-1150 GHz with SIS mixers and a sixth dual frequency band, for the 1410-1910 GHz range, with Hot Electron Bolometer Mixers (HEB). The Local Oscillator (LO) subsystem consists of a dedicated Ka-band synthesizer followed by 7 times 2 chains of frequency multipliers, 2 chains for each frequency band. A pair of Auto-Correlators and a pair of Acousto-Optic spectrometers process the two IF signals from the dual-polarization front-ends to provide instantaneous frequency coverage of 4 GHz, with a set of resolutions (140 kHz to 1 MHz), better than < 0.1 km/s. After a successful qualification program, the flight instrument was delivered and entered the testing phase at satellite level. We will also report on the pre-flight test and calibration results together with the expected in-flight performance.
International Conference on Space Optics — ICSO 2018, Jul 12, 2019
In this article the immersed gratings for the ESA Copernicus Sentinel-5 mission are presented. Th... more In this article the immersed gratings for the ESA Copernicus Sentinel-5 mission are presented. The manufacturing approach is shown and the optical performance of the SWIR-3 immersed gratings as well as the results of the environmental tests are discussed. The immersed gratings show an average efficiency of 60% and a wavefront error of 200 nm rms. The total integrated scatter over the complete stray-light hemisphere excluding ghosts from internal reflections is found to be 0.2% using a conservative estimate. A method for the derivation of the wavefront error from separate surface measurements is presented and the results are compared to measurements with an experimental Shack-Hartmann setup. The immersed gratings are produced by bonding a prism to a wafer with a grating. Environmental tests and testing at operational temperatures show the suitability of this approach for complex space optical components. The article concludes with possible improvements in the optical performance of future immersed gratings.
SPACOMM 2011, The …, 2011
The Heterodyne Instrument for the Far-Infrared onboard the ESA Herschel satellite is a heterodyne... more The Heterodyne Instrument for the Far-Infrared onboard the ESA Herschel satellite is a heterodyne spectrometer with unprecedented frequency range, resolution and sensibility. It is composed of two spectrometers, a Local Oscillator Unit, producing the mixing signals, a Focal Plane Unit, perfoming mixing and amplification, and an Instrument Control Unit, hosting a DSP where the On Board Software (OBS) runs. The OBS coordinates the other units, manages the interface with the spacecraft and monitors the instrument status. A synthetic description of the OBS organization and functioning is presented in this paper.
Microelectronic Engineering, Apr 1, 1988
Research was carried out on a voltage contrast detector in a scanning electron microscope. The fo... more Research was carried out on a voltage contrast detector in a scanning electron microscope. The form of the detector was investigated. Test techniques are reviewed as an introduction to the field of IC-testing. The physical background of secondary electron emission is discussed. The signal to noise ratio of voltage measurements for the spectrometer is calculated and compared with the theoretical maximum and values of conventional designs. Several voltage contrast detectors are described. The spectrometer is described and the influence of the magnetic field on the focusing properties of the primary system and the feasibility of a multiple focusing electron in a parallelizer and in the spectrometer was calculated with a ray tracing program. Experimental results are detailed.
X-ray calibration of the Electro-Optical Breadboard Model (EOBB) of the XXM Reflection Grating Sp... more X-ray calibration of the Electro-Optical Breadboard Model (EOBB) of the XXM Reflection Grating Spectrometer has been carried out at the Panter test facility in Germany. The EOBB prototype optics consisted of a four-shell grazing incidence mirror module followed by an array of eight reflection gratings. The dispersed x-rays were detected by an array of three CCDs. Line profile and efficiency
Advances in Optical and Electron Microscopy, 1991
EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy V, 1994
Space Optics 1994: Earth Observation and Astronomy, 1994
ABSTRACT The Reflection Grating Spectrometer (RGS) onboard the ESA satellite XMM (X-ray Multi Mir... more ABSTRACT The Reflection Grating Spectrometer (RGS) onboard the ESA satellite XMM (X-ray Multi Mirror mission) combines a high resolving power (approximately 400 at 0.5 keV) with a large effective area (approximately 200 cm(superscript 2)). The spectral range selected for RGS (5 - 35 angstroms) contains the K shell transitions of N, O, Ne, Mg, Al, Si and S as well as the important L shell transitions of FE. The resolving power allows the study of a wide variety of challenging scientific questions. Detailed temperature diagnostics are feasible as the ionization balance is a unique function of the distribution of the electron temperature. Density diagnostics are provided by studying He-like triplets where the ratio of the forbidden to intercombination lines varies with density. Other fields of interest include the determination of elemental abundances, the study of optical depth effects, velocity diagnostics by measuring Doppler shifts and the estimate of magnetic fields through the observation of Zeeman splitting. The resolving power is obtained by an array of 240 gratings placed behind the mirrors of the telescope, dispersing about half of the X-rays in two spectroscopic orders. The X-rays are recorded by an array of 9 large format CCDs. These CCDs are operated in the frame transfer mode. They are back illuminated as the quantum efficiency of front illuminated devices is poor at low energies because of their poly-silicon gate structure. To suppress dark current the CCDs are passively cooled. In order to obtain the effective area of about 200 cm(superscript 2), grating arrays and CCD cameras are placed behind two of the three XMM telescopes. A model of RGS was tested last autumn ('93) at the Panter long beam X-ray facility in Munich. The model consisted of a subset of four mirrors, eight representative gratings covering a small section of the inner mirror shells and a CCD camera containing three CCDs. The purpose of these tests was to verify the resolution and sensitivity of the instrument as a function of X-ray energy. Extensive simulations, using a Monte Carlo raytracing code, are used to interpret these tests. Preliminary results of these tests will be discussed and compared to the calculated response.
X-Ray Optics, Instruments, and Missions III, 2000
ABSTRACT
EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy VII, 1996
ABSTRACT The x-ray multi-mirror (XMM) mission is the second of four cornerstone projects of the E... more ABSTRACT The x-ray multi-mirror (XMM) mission is the second of four cornerstone projects of the ESA long-term program for space science, Horizon 2000. The payload comprises three co- aligned high-throughput, imaging telescopes with a FOV of 30 arcmin and spatial resolution less than 20 arcsec. Imaging CCD-detectors (EPIC) are placed in the focus of each telescope. Behind two of the three telescopes, about half the x-ray light is utilized by the reflection grating spectrometer (RGS). The x-ray instruments are co-aligned and measure simultaneously with an optical monitor (OM). The RGS instruments achieve high spectral resolution and high efficiency in the combined first and second order of diffraction in the wavelength range between 5 and 35 angstrom. The design incorporates an array of reflection gratings placed in the converging beam at the exit from the x-ray telescope. The grating stack diffracts the x-rays to an array of dedicated charge-coupled device (CCD) detectors offset from the telescope focal plane. The cooling of the CCDs is provided through a passive radiator. The design and performance of the instrument are described below.