The ARIEL InfraRed Spectrometer (AIRS) instrument will be implemented on board of the ARIEL (Atmospheric Remote‐sensing Infrared Exoplanet Large‐survey) space mission led by ESA, to study the atmosphere of exoplanets by providing low resolution spectrum of the observed targets over broad infrared wavelength range covering the [1,95-7,8] μm. The satellite will be launched by ARIANE 6 from Kourou in 2029 for a 4 years mission. AIRS is equipped with two integrated Focal Plane Assemblies (iFPA) each resulting of the assembly of two subsystem: the Focal Plane Array (FPA) and the Cold Front-End Electronic (CFEE). Each FPA is equipped with a detector H1RG from Teledyne whose cut-off wavelength had been tuned to fit the wavelength domain of interest. The CFEE is connected by a flex cable to the detector package and passively cooled between around 60K through the AIRS optical benches and the Optical Bench of the ARIEL payload. Two different structural models and four bread board models have been developed to validate and qualify the thermal and mechanical design and to validate the full electrical functional detection chain. The paper will describe all these models and the results obtained during the qualification campaign and the performance tests of the first iFPA model equipped with an eight micrometers cut-off detector. This paper describes also the dedicated cryostat and test benches developed, with associated safety, to check compliance with mission requirement at subsystem level.
AIRS is the infrared spectroscopic instrument of ARIEL: Atmospheric Remote‐sensing Infrared Exoplanet Large‐survey mission adopted in November 2020 as the Cosmic Vision M4 ESA mission and planned to be launched in 2029 by an Ariane 6 from Kourou toward a large amplitude orbit around L2 for a 4-year mission. Within the scientific payload, AIRS will perform transit spectroscopy of over 1000 exoplanets to complete a statistical survey, including gas giants, Neptunes, super-Earths and Earth-size planets around a wide range of host stars. All these collected spectroscopic data will be a major asset to answer the key scientific questions addressed by this mission: what are exoplanets made of? How do planets and planetary systems form? How do planets and their atmospheres evolve over time? The AIRS instrument is based on two independent channels covering 1.95-3.90 µm (CH0) and 3.90-7.80 µm (CH1) wavelength ranges with prism-based dispersive elements producing spectra of low resolutions R>100 in CH0 and R>30 in CH1 on two independent detectors. The spectrometer is designed to provide a Nyquist-sampled spectrum in both spatial and spectral directions to limit the sensitivity of measurements to the jitter noise and intra pixels pattern during the long (10 hours) transit spectroscopy exposures. A full instrument overview will be presented covering the thermo-mechanical design of the instrument functioning in a 60 K environment, up to the detection and acquisition chain of both channels based on 2 HgCdTe detectors actively cooled to below 42 K. This overview will present updated information of phase C studies, in particular on the assembly and testing of prototypes that are highly representative of the future engineering model that will be used as an instrument-level qualification model.
For several years, CEA-LETI has worked on the development of IR MCT detectors for low flux applications in scientific imaging. MCT has remarkable material properties that allow for highly performing detection, with high QEs and minimal dark currents. Currently, both Teledyne US and LETI-Lynred in France achieve dark currents in the range of a fraction of e/s/pixel for NIR imaging, utilizing the p-on-n extrinsic diode structure, for astronomy applications. As part of the NEOCAM project, Teledyne has demonstrated the ability to extend the cut-off wavelength to significantly longer wavelengths (10.3μm and recently 13μm) while keeping the dark current in the e/s range. Furthermore, LETI is presently enhancing its p-on-n technology to satisfy the demanding specifications of low-flux applications. Achieving very low dark current leakage and large diode polarisation plateaus is required to achieve SFD input stage ROIC operation and to reach such low dark current values. This entails the mitigation of tunnelling currents that appear in low-gap materials. In this report, we present the production of a 15μm pitch TV-size prototype array that operates in the LW range (8μm @ 35K). Dark current values as low as 0.5 e/s/pixel have been measured below 40K, and will be discussed.
Absolute Quantum Efficiency (QE) measurements are very demanding. To measure the QE of detectors from 0.8μm to 12.5μm a dedicated test bench has been built. The Quantix test bench relies on an optical design ensuring a uniform flat-field illumination of the detector. The illumination uniformity was measured with photodiodes built and calibrated at CEA/LETI. While performing QE measurements, the calibrated photodiode is placed in the vicinity of the detector to measure the incident flux. The Quantix test bench has been validated with a detector whose QE has been measured at the European Space Agency. In this paper, the test bench will be described in details and QE measurements performed on near infrared, MCT-based detectors will be presented. The intra-pixel response is also an important parameter to know as it can affect the accuracy of photometric and shape measurements. The Intrapix test bench has been specifically designed for this measurement, using the Talbot effect to simultaneously measure the intra-pixel response in a large number of subareas of a given detector, from 0.5 μm to 12 μm. The paper will give a brief status of the test bench development.
The program Astronomy European Infrared Detector (ASTEROID), funded by the European Union through H2020 (under Grant Agreement n°730161), aims at enabling Europe to acquire the technology and knowledge necessary to manufacture 2k² high performance IR detectors. To reach these goals 9 detectors have been manufactured at Lynred and characterized at the Astrophysics Department of CEA. ASTEROID detectors are 640×512 pixels arrays with a pixel pitch of 15 μm. The detectors are p-on-n technology, with 15 μm pixel pitch, with a cut-off wavelength of 2.1 μm. In the detector architecture, the MCT light-sensitive layer is hybridized on a Source Follower Detector (SFD) Read Out Integrated Circuit (ROIC) via indium bumps. In this paper, the characterization results of ASTEROID detectors will be presented. The best detectors show extremely low dark current around 0.001 e-/s/pix, which is equivalent to standard H2RG IR detector (widely used in the IR domain for astrophysics applications). The quantum efficiency (QE) of these detectors has also been measured on a dedicated test bench and will be presented. ASTEROID detectors demonstrated a QE of 70 %.
AIRS is the infrared spectroscopic instrument of ARIEL: Atmospheric Remote‐sensing Infrared Exoplanet Large‐survey mission selected in March 2018 as the Cosmic Vision M4 ESA mission and planned to be launched in 2029 by an Ariane 6 from Kourou toward a large amplitude orbit around L2 for a 4 year mission. Within the scientific payload, AIRS will perform transit spectroscopy of over a 1000 of exoplanets to complete a statistical survey, including gas giants, Neptunes, super-Earths and Earth-size planets around a wide range of host stars. All these collected spectroscopic data will be a major asset to answer the key scientific questions addressed by this mission: what are the exoplanets made of? How do planets and planetary system form? How do planets and their atmospheres evolve over time? The AIRS instrument is based on two independent channels covering the CH0 [1.95-3.90] µm and the CH1 [3.90-7.80] µm wavelength range with prism-based dispersive elements producing spectrum of low resolutions R<100 in CH0 and R<30 in CH1 on two independent detectors. The spectrometer is designed to provide spectrum Nyquist-sampled in both spatial and spectral directions to limit the sensitivity of measurements to the jitter noise and intra pixels pattern during the long (10 hours) transit spectroscopy exposures. A full instrument overview will be presented covering the thermal mechanical design of the instrument functioning in a 60 K cold environment, up to the detection and acquisition chain of both channels based on 2 HgCdTe detectors actively cooled down below 42 K. This overview will present updated information of phase B2 studies in particular with the early manufacturing of prototype for key elements like the optics, focal-plane assembly and read-out electronics as well as the results of testing of the IR detectors up to 8.0 μm cut-off.
Euclid-VIS is the large format visible imager for the ESA Euclid space mission in their Cosmic Vision program, scheduled for launch in 2021. Together with the near infrared imaging within the NISP instrument, it forms the basis of the weak lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-900 nm over a field of view of ~0.5 deg2 . By combining 4 exposures with a total of 2260 sec, VIS will reach to deeper than mAB=24.5 (10s) for sources with extent ~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable point spread function (PSF) over a wide survey area of 15000 deg2 to measure the cosmic shear from nearly 1.5 billion galaxies to high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also provide a legacy dataset with an unprecedented combination of spatial resolution, depth and area covering most of the extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Consortium during the period up to the beginning of the Flight Model programme
In the frame work of the ESA Euclid mission to be launched in 2021, the Euclid Consortium is developing an extremely large and stable focal plane for the VIS instrument. After an extensive phase of definition and study over 4 years made at CEA on the thermo-mechanical architecture of that Focal Plane, the first model (Structural and Thermal Model) has been assembled qualified and delivered to MSSL in June 2017. The VIS Focal Plane Assembly integrates 36 CCDs (operated at 153K) connected to their front end electronics (operated at 280K). This Focal Plane will be the largest focal plane (∼0.6 billion pixels) ever built for space application after the GAIA one. The CCDs are CCD-273 type specially designed and provided by the Teledyne e2v company under ESA contract. The Structural and Thermal Model is fully representative of the Flight Model regarding the thermo-mechanical architecture. The STM FPA thus integrates 36 CCDs representative of the flight model except for the detection function. We have implemented specific equipment in order to perform the metrology of the full FPA. It consists of the measurement of the flatness of the full camera as well as the determination of the position of its 36 CCDs. The purpose is to measure the dimension of the sensitive area and to localize each CCDs’ image area with an uncertainty of +/-50 µm in X- and Y-directions. These positions are then given at room temperature in the reference frame of the main FPA structure that is interfaced with the Euclid telescope. The metrology also implies the verification of the flatness of the focal plane in the range of +/-60 μm with an uncertainty of +/-10 μm. Indeed, we must check that the design and the assembly of the FPA meet this requirement that consists of considering that the full photosensitive area is included in a volume of 120 μm high. Based on a marble with a flatness of 10 μm and two motorized linear stages, the test bench combines a CCD camera and a confocal sensor. The camera allows localizing the four fiducial crosses of each CCD-273 and thus to define a grid of 9 equally spaced points on the image area. We can then measure thanks to the confocal sensor the flatness of the full sensitive area in 324 points across the FPA. In this paper, we describe the test bench and the method that we have validated for the STM program. We thus report the results for the STM FPA5 with an estimation of the uncertainty of +/-10 µm for the flatness measurement and around +/- 24 μm (including a coverage factor of 2 for a level of confidence of 95%) for the relative position of the CCDs, which corresponds to twice the pixel size of the CCDs. We finally indicate the improvement that we plan to implement to better estimate the CCDs' position in the FPA coordinates.
In the frame work of the ESA Euclid mission to be launched in 2020, the Euclid Consortium is developing an extremely large and stable focal plane for the VIS instrument. After an extensive phase of definition and study over 4 years made at CEA on the thermo-mechanical architecture of that Focal Plane, the first model (Structural and Thermal Model) has been assembled qualified and delivered to MSSL in June 2017.
The VIS Focal Plane Assembly integrates 36 CCDs (operated at 150K) connected to their front end electronics (operated at 280K). This Focal Plane will be the largest focal plane (~0.6 billion pixels) ever built for space application after the GAIA one. The CCDs are CCD273 type specially designed and provided by the Teledyne e2v company under ESA contract, front end electronics is studied and provided by MSSL.
The Structural and Thermal Model is fully representative of the Flight Model regarding the thermo-mechanical architecture. As the instrument development philosophy follows a Proto Flight approach this choice has been made very early in the development program in order to reduce the risk on the PFM program. So the AIT/AIV plan has been built in order to fully validate since the STM program the overall integration, verification and qualification sequences, taking into account the very stringent cleanliness requirement. The STM FPA integrates 36 CCDs representative of the flight model except for the detection function. Electrical configuration of the front end electronics provides electrical interface in order to power the CCDs and check integrity of all the electrical links to CCDs.
In this paper we first recall the architecture of the VIS-FPA and especially the solutions proposed to cope with the scientific needs of an extremely stable focal plane, both mechanically and thermally leading to a SiC structure. The modular architecture concept, considered as a key driver for such big and complex focal plane is detailed. Parallel to that, the integration workflow including verification steps is fully depicted including specific aspects linked to the use of SiC. Validation and qualification test program is described. A summary of geometrical measurements, thermal balance tests and vibrations tests including the main Ground Support Equipment description are reported.
Keyword list: Euclid, CCD, SiC, focal plane, architecture, integration
KEYWORDS: Sensors, X-rays, Satellites, Field programmable gate arrays, Calibration, Space operations, Electroluminescence, Optimal filtering, Spectroscopy, Digital signal processing
Astro-H1 is a JAXA/NASA X-ray satellite launched in 17th Feb. 2016. The hard X-ray imager (HXI)2 is a Si/CdTe stacked detector system which is placed in the focus of a hard x-ray telescope. HXI constitute one of the four different instruments onboard Astro-H.
We are presenting the current status of a stacked detector setup which consists of two mini-HXI double sided CdTe strip detectors (CdTe DSDs)|similar to those used in HXI|that are read out with the low-noise readout ASIC IDeF-X BD. We describe the configuration of the setup, its spectroscopic performance, and a long-term operation of the setup. The long-term test simulates the orbital operation of HXI using identical detector temperatures, bias voltages, and switch-on/switch-off cycles with the goal to study the detector stability and the evolution of its performance during operation.
One of the main challenges for current and near future space experiments is the increase of focal plane complexity in terms of amount of pixels. In the frame work of the ESA Euclid mission to be launched in 2020, the Euclid Consortium is developing an extremely large and stable focal plane for the VIS instrument. CEA has developed the thermomechanical architecture of that Focal Plane taking into account all the very stringent performance and mission related requirements. The VIS Focal Plane Assembly integrates 36 CCDs (operated at 150K) connected to their front end electronics (operated at 280K) as to obtain one of the largest focal plane (∼0.6 billion pixels) ever built for space application after the GAIA one. The CCDs are CCD273 type specially designed and provided by the e2v company under ESA contract, front end electronics is studied and provided by MSSL. In this paper we first recall the specific requirements that have driven the overall architecture of the VIS-FPA and especially the solutions proposed to cope with the scientific needs of an extremely stable focal plane, both mechanically and thermally. The mechanical structure based on SiC material used for the cold sub assembly supporting the CCDs is detailed. We describe also the modular architecture concept that we have selected taking into account AIT-AIV and programmatic constraints.
The 6 K cooled primary mirror of the SPICA observatory, to be launched in 2018, allows a photometry gain in
sensitivity in the far infrared of more than two orders of magnitude when compared with current instrumentation in
space. All the proposed detector solutions will have to deploy radically different solutions from previous developments
to cope with the extremely low background and very low power budgets available at all the temperature stages. We
present the current design of very large "all Silicon" filled Bolometer Arrays cooled below 100 mK, and the solutions we
develop for the BASIC (Bolometer Arrays for the All Silicon SAFARI Imaging Camera) focal planes of SAFARI. They
will cover simultaneously three wavelength bands between 30 and 210 μm.
The ArTeMiS submillimetric camera will observe simultaneously the sky at 450, 350 and 200 μm using 3 different focal
planes made of 2304, 2304 and 1152 bolometric pixels respectively. This camera will be mounted in the Cassegrain
cabin of APEX, a 12 m antenna located on the Chajnantor plateau, Chile.
To realize the bolometric arrays, we have adapted the Silicon processing technology used for the Herschel-PACS
photometer to account for higher incident fluxes and longer wavelengths from the ground. In addition, an autonomous
cryogenic system has been designed to cool the 3 focal planes down to 300 mK. Preliminary performances obtained in
laboratory with the first of 3 focal planes are presented.
Latest results obtained in 2009 with the P-ArTeMiS prototype camera are also discussed, including massive protostellar
cores and several star forming regions that have been clearly identified and mapped.
The CEA/LETI and CEA/SAp started the development of far-infrared filled bolometer arrays for space applications
over a decade ago. The unique design of these detectors makes possible the assembling of large focal planes
comprising thousands of bolometers running at 300 mK with very low power dissipation. Ten arrays of 16x16
pixels were thoroughly tested on the ground, and integrated in the Herschel/PACS instrument before launch in
May 2009. These detectors have been successfully commissioned and are now operating in their nominal environment
at the second Lagrangian point of the Earth-Sun system. In this paper we briefly explain the functioning
of CEA bolometer arrays, and we present the properties of the detectors focusing on their noise characteristics,
the effect of cosmic rays on the signal, the repeatability of the measurements, and the stability of the system.
ArTeMiS is a camera designed to operate on large ground based submillimetric telescopes in the 3 atmospheric windows
200, 350 and 450 µm. The focal plane of this camera will be equipped with 5760 bolometric pixels cooled down at 300
mK with an autonomous cryogenic system. The pixels have been manufactured, based on the same technology processes
as used for the Herschel-PACS space photometer. We review in this paper the present status and the future plans of this
project.
A prototype camera, named P-ArTeMiS, has been developed and successfully tested on the KOSMA telescope in 2006 at
Gornergrat 3100m, Switzerland. Preliminary results were presented at the previous SPIE conference in Orlando (Talvard
et al, 2006). Since then, the prototype camera has been proposed and successfully installed on APEX, a 12 m antenna
operated by the Max Planck Institute für Radioastronomie, the European Southern Observatory and the Onsala Space
Observatory on the Chajnantor site at 5100 m altitude in Chile. Two runs have been achieved in 2007, first in March and
the latter in November. We present in the second part of this paper the first processed images obtained on star forming
regions and on circumstellar and debris disks. Calculated sensitivities are compared with expectations. These illustrate
the improvements achieved on P-ArTeMiS during the 3 experimental campaigns.
Astronomical observations at sub-millimetre wavelengths are limited either by the angular resolution of the telescope or
by the sensitivity and field of view of the detector array. New generation of radio telescopes, such as the ALMA-type
antennas on Chajnantor plateau in Chile, can overcome these limitations if they are equipped with large detector arrays
made of thousands of sensitive bolometer pixels.
Instrumentation developments undertaken at CEA and based on the all silicon technology of CEA/Leti are able to
provide such large detector arrays. The ArTeMiS project consists in developing a camera for ground-based telescopes
that operates in two sets of atmospheric windows at 200-450 μm (channel 1) and 800-1200 μm (channel 2).
ArTeMiS-1 consists in grid bolometer arrays similar to those developed by CEA for the Herschel Space Observatory. A
prototype camera operating in this first atmospheric window was installed and successfully tested in March 2006 on the
KOSMA telescope at Gornergrat (Switzerland) in collaboration with the University of Cologne. ArTeMiS-2 will consist
either in antenna-coupled bolometer arrays or specific mesh bolometer arrays.
By the end of 2008, ArTeMiS cameras could be operated on 10m-class telescopes on the Chajnantor ALMA site, e.g.,
APEX, opening new scientific prospects in the study of the early phases of star formation and in cosmology, in the study
of the formation of large structures in the universe. At longer term, installation of such instrumentation at Dome-C in
Antarctica is also under investigation. The present status of the ArTeMiS project is detailed in this paper.
A new kind of bolometric architecture has been successfully developed for the PACS photometer onboard the Herschel submillimeter observatory. These new generation CCD-like arrays are buttable and enable the conception of large fully sampled focal planes. We present a feasibility study of the adaptation of these bolometer arrays to ground-based submillimeter telescopes. We have developed an electro-thermal numerical model to simulate the performances of the bolometers under specific ground-based conditions (different wavelengths and background powers for example). This simulation permits to determine the optimal parameters for each condition and shows that the bolometers can be background limited in each transmission window between 200 and 450 microns. We also present a new optical system that enables to have a maximum absorption of the bolometer in each atmospheric windows. The description of this system and measurements are shown.
The development program of the flight model imaging camera for the PACS instrument on-board the Herschel
spacecraft is nearing completion. This camera has two channels covering the 60 to 210 microns wavelength
range. The focal plane of the short wavelength channel is made of a mosaic of 2×4 3-sides buttable bolometer
arrays (16×16 pixels each) for a total of 2048 pixels, while the long wavelength channel has a mosaic of 2 of the
same bolometer arrays for a total of 512 pixels. The 10 arrays have been fabricated, individually tested and
integrated in the photometer. They represent the first filled arrays of fully collectively built bolometers with
a cold multiplexed readout, allowing for a properly sampled coverage of the full instrument field of view. The
camera has been fully characterized and the ground calibration campaign will take place after its delivery to
the PACS consortium in mid 2006. The bolometers, working at a temperature of 300 mK, have a NEP close
to the BLIP limit and an optical bandwidth of 4 to 5 Hz that will permit the mapping of large sky areas.
This paper briefly presents the concept and technology of the detectors as well as the cryocooler and the warm
electronics. Then we focus on the performances of the integrated focal planes (responsivity, NEP, low frequency
noise, bandwidth).
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