document title / titre du document TRP W ORK PLAN ... - emits - ESA

TRP Work Plan 2005-2007
Description of Activities
TEC-SB/7935/dc
12/Feb/09
TRP Reference:
Title:
T201-06SC
Active Pixel Sensor Focal Plane Assembly for NIR
The main objective of this activity is to develop, fabricate and validate an APS sensor to cover the wavelength range
0.4-2.2um, possibly extending the wavelength range to 2.5um to be used as sensor onboard the BepiColombo mission.
Previous development activity was mainly driven by European military needs and more recently, earth observation
programmes. In the framework of the earth observation programme, a 256x1000pixel focal plane array has been developed
and flown (SWIR hyperspectral application); however the sensor is targetted to the SWIR range. A cut-off at 0.8um is due to
the CdTe substrate on which the HgCdTe (MCT) detector is grown. In order to fullfill the science requirements of
BepiColombo and indeed potential future scientific satellites, there is the need to further develop the technology in the
following areas:
1) reduction of the thermal current; 2) extension of the wavelength range down to 400nm; 3) radiation hardening/verification.
A compact focal plane assembly shall be attempted for mapping spectroscopy in the visible and NIR (Near InfraRed)
wavelengths. Possible technologies to be explored are back-thinned MercuryCadmiumTelluride (MCT) or
IndiumGalliumArsenide (InGaAs). The detector should be part of a breadboard for the imager/spectograph VIHI onboard
BepiColombo. This activity will benefit from a experience gained in a similar activity, concluded with D/EOP, where a 250-1000
MCT detector was developed. A further development and optimization is needed in order to accomodate the wavelength
range from 0.4 to 2.2 microns.
Deliverables:
Compact focal plane breadboard.
Current TRL: TRL2-3 Target TRL: TRL4 Application Need/Date: TRL6 by 2009
Application/Mission: Bepi Colombo Contract Duration: 24 months
SW Clause : - Dossier0 Ref.: -
Consistency with Harmonisation
Roadmap and Conclusions:
TRP Reference:
Title:
Active Pixel Sensor Focal Plane Assembly for NIR - Additional work
The main objective of the original activity has been to develop, fabricate and validate an APS sensor to cover the wavelength
range 0.4-2.2um, possibly extending the wavelength range to 2.5um to be used as sensor onboard the BepiColombo mission.
Previous development activity was mainly driven by European military needs and more recently, earth observation
programmes. In the framework of the earth observation programme, a 256x1000pixel focal plane array was developed and
flown (SWIR hyperspectral application); however the sensor is targetted to the SWIR range. A cut-off at 0.8um is due to the
CdTe substrate on which the HgCdTe (MCT) detector is grown. In order to fullfill the science requirements of BepiColombo
and indeed potential future scientific satellites, there has been the need to further develop the technology in the following
areas: 1) reduction of the thermal current; 2) extension of the wavelength range down to 400nm; 3) radiation
hardening/verification.
A compact focal plane assembly has been attempted for mapping spectroscopy in the visible and NIR (Near InfraRed)
wavelengths. Possible technologies being explored are back-thinned MercuryCadmiumTelluride (MCT) or
IndiumGalliumArsenide (InGaAs). The development is in a first instance intended for the imager/spectograph VIHI onboard
BepiColombo, but could serve future missions requiring hyperspectral capability from visible to NIR wavelength range. This
activity benefits from the experience gained in a similar activity, concluded with D/EOP, where a 250-1000 MCT detector was
developed. Further development and optimization has been needed in order to accomodate the wavelength range from 0.4 to
2.2 microns.
In order to cover the additional development required when carefully reviewing the Bepi Colombo missions needs, a CCN will
be placed.
It will allow to cope with with a number of technology issues. In fact, the manufacturing and testing of a hyperspectral detector
(0.4 to 2.2 um) for the Bepi Colombo/VIHI instrument appears to be extremely challenging at many levels. Due to the limited
budget, the detector concept proposed by SOFRADIR is heavily relying on heritage of a previous D/EOP contract. This
heritage is particularly obvious for the CMOS readout circuitry, which will be entirely used as such.
This major design parameter has led to the need of total ionizing dose tests to prove the capability of the readout to withstand
the harsh environment of Bepi Colombo. Within the original contract, it was possible to accommodate only one TID test, using
an existing device of the EOP. However it is clear that this unique test will only respond very partially to the radiation
tolerance, a second test would definitely give more credit to the campaign. The outcome of the test will determine whether the
BepiColombo/VIHI team will use this detector or if they need to rely on a US backup (Rockwell or Raytheon). It is worth noting
that the results of this radiation campaign may also be of particular interest for EOP and its future developments. Last but not
least, a better knowledge of the TID behavior of the device will considerably improve our understanding of the proton tests,
aiming at studying the potential displacements damage effects occurring in the thinned Mercury Cadmium Telluride substrate.
The tests which will be carried out by SOFRADIR will cover the main electro-optical characteristics of the final device. Due to
timescale and technical limitations of SOFRADIR’s test bench, some specific tests will not be achievable within this contract
(e.g. spot scanning for visible MTF…). Therefore, it is of prime interest to have the possibility to carry out additional tests on
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