Within the European Global Monitoring for Environment and Security (GMES) program, the Sentinel-2 mission will
provide multi-spectral observations of the Earth surface. The Multi-Spectral Instrument (MSI) developed by Astrium, on
board the Sentinel-2 satellite, includes a SWIR channel. Sofradir is in charge of the development, qualification and
manufacturing of the infrared detector basis of this SWIR channel.
This development relies on Sofradir heritage in terms of design and production of infrared detectors for space
applications, and is based on the building blocks validated by Sofradir in the frame of ESA breadboarding program for
SWIR hyper-spectral detector development. What's more, the detector relies on the use of a high reliability 15 μm pitch
hybrid Mercury Cadmium Telluride (MCT) technology.
Each Sentinel-2 SWIR detector (12 detectors/instrument x 2 satellites) is comprised of an MCT elementary detector
including 3 detection lines with a length of 1298 pixels with 15 μm pitch for detection in the 1.3-2.3 μm range, and is
integrated into a compact sealed package filled with helium. This device will be used in the 170-200K range.
This paper describes the design of the Sentinel-2 SWIR detector. It also presents the performances and the first tests
carried out on representative models.
The Japanese Aerospace Exploration Agency (JAXA) will be conducting the Global Change Observation Mission
(GCOM) for monitoring of global environmental change. SGLI (Second Generation Global Imager) is an optical sensor
on board GCOM-C (Climate), that includes a Long Wave IR Detector (LWIRD) sensitive up to about 13 μm. SGLI will
provide high accuracy measurements of the atmosphere (aerosol, cloud ...), the cryosphere (glaciers, snow, sea ice ...),
the biomass and the Earth temperature (sea and land).
Sofradir is a major supplier of Space industry based on the use of a Space qualified MCT technology for detectors from
0.8 to 15 μm. This mature and reproducible technology has been used for 15 years to produce thousands of LWIR
detectors with cut-off wavelengths between 9 and 12 μm.
NEC Toshiba Space, prime contractor for the Second Generation Global Imager (SGLI), has selected SOFRADIR for its
heritage in space projects and Mercury Cadmium Telluride (MCT) detectors to develop the LWIR detector.
This detector includes two detection circuits for detection at 10.8 μm and 12.0 μm, hybridized on a single CMOS readout
circuit. Each detection circuit is made of 20x2 square pixels of 140 μm. In order to optimize the overall performance,
each pixel is made of 5x5 square sub-pixels of 28 μm and the readout circuit enables sub-pixel deselection. The MCT
material and the photovoltaic technology are adapted to maximize response for the requested bandwidths: cut-off
wavelengths of the 2 detection circuits are 12.6 and 13.4 μm at 55K. This detector is packaged into a sealed housing for
full integration into a Dewar at 55K.
This paper describes the main technical requirements, the design features of this detector, including trade-offs regarding
performance optimization, and presents preliminary electro-optical results.
Current multilayer designs for 10-80 keV hard X-ray telescope missions have focused primarily on the proven
properties of W and Pt based multilayer coatings. Recently a number of new material combinations and coating
capabilities have emerged which allows for more elaborate designs that can further extend the energy band of current
mission designs as well as avoid some of the unwanted absorption edge effects in the effective area near potentially
important line emission energies. These new design possibilities are investigated for current hard X-ray mission designs.
The new material combinations to be considered are recently proven capabilities of enhanced NiV/C coatings and
NiV/SiC coatings in conjuction with the well-established W based coatings.
Graded depth multi-layer coatings have the potential to optimise the performance of X-ray reflective surfaces for improved energy response. A study of deposition techniques on silicon substrates representative of the XEUS High Performance Pore Optics (HPO) technology has been carried out. Measurements at synchrotron radiation facilities have been used to confirm the excellent performance improvements achievable with Mo/Si and W/Si multilayers. Future activities that will be necessary to implement such coatings in the HPO assembly sequence are highlighted. Further coating developments that may allow an optimisation of the XEUS effective area in light of potential changes to science requirements and telescope configurations are also identified. Finally an initial measurement of effects of radiation damage within the multilayers is reported.