The RAPID camera is an Avalanche Photo Diode array allowing very fast observation from the optical to the infrared with still a low noise per read. The camera born from a large collaboration within the FUI/FOCUS is intensively tested at IPAG (Grenoble) on an interferometric bench and will soon replace the actual camera of the PIONIER interferometer mounted on the visitor focus of the VLTi. We shortly present here the PIONIER instrument design and success to then focus on the RAPID tested performances. We will then resume the performance tests made on sky with the PIONIER. The RAPID camera is the first IR APD matrix ever mounted on an on-sky astronomical instrument. We show here how this fast, low-noise, large-band and sensitive camera improves PIONIER and the optical interferometry in general.
This paper describes the recent developments of Mercury Cadmium Telluride (MCT) infrared technologies in France at Sofradir and CEA-LETI made in the frame of the common laboratory named DEFIR. Among these developments, one can find the crystal growth of high quality and large Cadmium Zinc Telluride (CZT) substrates which is one of the fundamental keys for high quality and affordable detectors. These last years, a great effort was done on this topic and also on MCT epilayer process from Short Waves (SW) to Very Long Waves (VLW). These developments about the quality of the material are needed for the challenge of the High Operating Temperature (HOT). Over these lasts years, the operating temperature of n/p MCT detectors was increase of several tens of Kelvin. In addition the development of the p/n MCT technology that reduces dark current by a factor ~100 saves about twenty Kelvin more. The next step for the increase in operating temperature will be the complex photodiodes architectures using molecular beam epilayer. The reduction of the pixel pitches is another challenge for infrared technologies for Small Weight and Power (SWAP) detectors. Moreover, this reduction allows the increase in the resolution and consequently in the detection range of the systems. In addition, last results on 3rd generation detectors such as multicolor focal plan arrays, 2D, 3D, low noise and high images rate focal plane array using Avalanche Photodiose (APD) are described.
The purpose of this paper is to give an overview of the state of the art wavefront sensor detectors developments held in
Europe for the last decade.
The success of the next generation of instruments for 8 to 40-m class telescopes will depend on the ability of Adaptive
Optics (AO) systems to provide excellent image quality and stability. This will be achieved by increasing the sampling,
wavelength range and correction quality of the wave front error in both spatial and time domains.
The modern generation of AO wavefront sensor detectors development started in the late nineties with the CCD50
detector fabricated by e2v technologies under ESO contract for the ESO NACO AO system. With a 128x128 pixels
format, this 8 outputs CCD offered a 500 Hz frame rate with a readout noise of 7e-.
A major breakthrough has been achieved with the recent development by e2v technologies of the CCD220. This
240x240 pixels 8 outputs EMCCD (CCD with internal multiplication) has been jointly funded by ESO and Europe under
the FP6 programme. The CCD220 and the OCAM2 camera that operates the detector are now the most sensitive system
in the world for advanced adaptive optics systems, offering less than 0.2 e readout noise at a frame rate of 1500 Hz with
negligible dark current. Extremely easy to operate, OCAM2 only needs a 24 V power supply and a modest water cooling circuit. This system, commercialized by First Light Imaging, is extensively described in this paper. An upgrade of
OCAM2 is foreseen to boost its frame rate to 2 kHz, opening the window of XAO wavefront sensing for the ELT using 4
synchronized cameras and pyramid wavefront sensing.
Since this major success, new developments started in Europe. One is fully dedicated to Natural and Laser Guide Star
AO for the E-ELT with ESO involvement. The spot elongation from a LGS Shack Hartman wavefront sensor
necessitates an increase of the pixel format. Two detectors are currently developed by e2v. The NGSD will be a 880x840
pixels CMOS detector with a readout noise of 3 e (goal 1e) at 700 Hz frame rate. The LGSD is a scaling of the NGSD
with 1760x1680 pixels and 3 e readout noise (goal 1e) at 700 Hz (goal 1000 Hz) frame rate. New technologies will be
developed for that purpose: advanced CMOS pixel architecture, CMOS back thinned and back illuminated device for
very high QE, full digital outputs with signal digital conversion on chip. In addition, the CMOS technology is extremely
robust in a telescope environment. Both detectors will be used on the European ELT but also interest potentially all giant
telescopes under development.
Additional developments also started for wavefront sensing in the infrared based on a new technological breakthrough
using ultra low noise Avalanche Photodiode (APD) arrays within the RAPID project. Developed by the SOFRADIR and
CEA/LETI manufacturers, the latter will offer a 320x240 8 outputs 30 microns IR array, sensitive from 0.4 to 3.2
microns, with 2 e readout noise at 1500 Hz frame rate. The high QE response is almost flat over this wavelength range.
Advanced packaging with miniature cryostat using liquid nitrogen free pulse tube cryocoolers is currently developed for
this programme in order to allow use on this detector in any type of environment. First results of this project are detailed
These programs are held with several partners, among them are the French astronomical laboratories (LAM, OHP,
IPAG), the detector manufacturers (e2v technologies, Sofradir, CEA/LETI) and other partners (ESO, ONERA, IAC,
GTC). Funding is: Opticon FP6 and FP7 from European Commission, ESO, CNRS and Université de Provence,
Sofradir, ONERA, CEA/LETI and the French FUI (DGCIS).
This paper describes the recent developments of Mercury Cadmium Telluride (MCT) infrared technologies in France at
Sofradir and CEA-LETI made in the frame of the common laboratory named DEFIR.
Among these developments, one can find the crystal growth of high quality and large Cadmium Zinc Telluride (CZT)
substrates which is one of the fundamental keys for high quality and affordable detectors. These last years, a great effort
was done on this topic and also on MCT epitaxy layer process from Short Waves (SW) to Very Long Waves (VLW).
These developments about the quality of the material are needed for the challenge of the High Operating Temperature
(HOT). Over these lasts years, the operating temperature of n-on-p MCT detectors was increase of several tens of
Kelvin. In addition the development of the p-on-n MCT technology that reduces dark current by a factor ~100 saves
about twenty Kelvin more. The next step for the increase in operating temperature will be the complex photodiodes
architectures using molecular beam epitaxy layer.
The reduction of the pixel pitches is another challenge for infrared technologies for Small Weight and Power (SWAP)
detectors. Moreover, this reduction allows the increase in the resolution and consequently in the detection range of the
In addition, last results on 3rd generation detectors such as multicolor focal plan arrays, 2D, 3D, low noise and high
images rate focal plane array using Avalanche Photodiode (APD) are described.
Cooled IR technologies are challenged for answering new system needs like the reduction of power consumption. This
reduction is requested in new IR system design in particular for cooled IR detection. The goal is to reduce system sizes,
to increase system autonomies and reliabilities and globally to reduce system costs. One of the key drivers for cooled
systems is the cooler and the operating temperature. As far as operating temperature is concerned, Sofradir and CEALETI
LIR put a lot of efforts to increase the operating temperature of IR MCT detectors. The n/p and p/n MCT
technologies are improved to operate at high temperature with good performances and particularly with low rate of
defective pixels. These detectors operate in the MW blue band, MW and LW. In addition complex structures like nBn
structures are developed to go further in the high operating temperature. Results are presented and discussed.
This paper describes the status of MCT IR technology in France at Leti and Sofradir. This concerns first evolution of
crystal growth of large CZT for substrates, and MCT epilayers grown by LPE and MBE. A focus will be made on
extrinsic doping of MCT with Indium and Arsenic for device fabrication. Evolution of detector technology will also be
considered for detectors that operate from NIR/SWIR to VLWIR, moving from an n on p vacancy doped technology to a
fully extrinsically doped p on n device architecture. Last results on 3rd generation detectors such as multicolor FPAs,
HOT detectors and 2D or 3D FPAs that use MCT APD will also be described. Moving to larger FPAs, pixel pitch
reduction become mandatory and technology evolution to achieve this goal will be presented .Then, cost reduction
achievement through more compact systems that operate at higher temperature and/or integrate optical functions inside
the cryostat will also be considered.
CEA-Leti has developed a dual mode infrared array detector for passive (thermal) or active 2D and 3D imaging. Very
high sensitivity in 3D mode of operation is achieved by using an HgCdTe avalanche photodiode array with linear gain.
The 30 μm pitch detector array is hybridized to a 320x256 pixels Readout Integrated Circuit (ROIC). In passive mode,
the 3.6x106 e- well capacity and the low noise of the ROIC allow to reach photon noise limited NETD. For active
imaging mode, each pixel measures the time of arrival (3D) and the intensity (2D) of one laser pulse. A sensor based on
a detector array with a cut off wavelength of 4.6μm at 80K was fabricated and tested. This paper describes the pixel
architecture and presents ranging performances obtained in laboratory conditions. The first 2D and 3D active videos
obtained during a field trial of our focal plane array are presented.
HgCdTe (Mercury Cadmium Telluride / MCT) staring arrays for infrared detection do show constant
improvements regarding their compactness and performances.
Among the new detectors, the family of 15 μm pixel pitch detectors is offering a mid-TV format (384 x 288), a
TV format (640 x 512) and a HD-TV format (1280 x 1024). Each detector is available in a SWaP configuration
(meaning dedicated to applications requiring low Size, Weight and Power)
Thanks to recent improvements and new technological breakthrough, the MCT technology allows operating
detectors at higher temperature, in order to save power consumption at system level. In parallel, the 15μm pitch
permits to reach challenging density and spatial resolution. These Focal Plane Arrays (FPA) are proposed in
different tactical dewars, corresponding to various systems solutions.
Cooled IR technologies are challenged for answering new system needs like the reduction of energy. This reduction is
requested in new IR system design in particular for cooled IR detection. The goal is to reduce system sizes, to increase
system autonomies and reliabilities and globally to reduce system costs!
One of the key drivers for cooled systems is the cooler and the operating temperature. As far as operating temperature is
concerned, Sofradir put a lot of efforts for years for adapting its technologies to increase the operating temperatures of IR
detectors. Main examples are dealing with long wave staring arrays based on QWIP technology and on MCT technology
as well as medium wave staring arrays using MCT technologies.
This paper presents an overview of the very recent developments of the MCT infrared detector technology developed by
CEA-LETI and Sofradir in France for next generation of applications. New applications require high sensitivity and dual
The Avalanche PhotoDiodes (APD) technology opens new interesting fields of investigation for low flux applications
and fast detectors for laser imaging. IR sensors for this type of application are synchronized with eye-safe lasers, and
have to detect a weak signal backscattered from the target on the order of 10 photons per pulse. They also have to be
able to operate with a very short integration time, typically one hundred nanoseconds, in order to gate the backscattered
signal around the target. In partnership with Sofradir, CEA/LETI (France) has developed high quality MCT avalanche
photodiodes satisfying these requirements. In parallel, specific studies have been carried out at the Read-Out Circuit
level to develop optimized architectures. Thanks to these advances, a new Integrated Dewar Detector Cooler Assembly
has been developed. This new product presented in this paper is the first step in a road-map to address low flux infrared
sensors in the next few years.
In parallel, the development of dual-band infrared detectors has been the core of intense research and technological
improvements for the last ten years. New TV (640 x 512 pixels) format detectors of 24μm pixel pitch is available. It is
proposed with MWIR/MWIR or MWIR/LWIR dual band sensitivity integrated in dedicated tactical Dewars. At present,
focused on pixel pitch reduction, Sofradir is carrying out optimization of the materials quality, photodiode design as well
as flip-chip bonding process. 20 μm pixels have demonstrated dual color key performances (quantum efficiency, optical
fill factor, and pixel operability) in accordance with mono-spectral structures. Results are presented in this paper.
HgCdTe (Mercury Cadmium Telluride / MCT) staring arrays for infrared detection demonstrate constant improvements regarding their compactness and performances.
Among the new detectors, the family of 15 µm pixel pitch detectors is offering a mid-TV format (384 × 288), a TV format (640 × 512) and a HD-TV format (1280 × 1024). The latest development dealing with the mid-TV format is performed according to very challenging specifications regarding compactness and low power consumption. Thanks to recent improvements, the MCT technology allows to operate detectors at higher temperature, in order to save power consumption at system level. In parallel, the 15μm pitch enables to reach challenging density and spatial resolution. This Focal Plane Arrays (FPA) is proposed in different tactical dewars, corresponding to various systems solutions.
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.
HgCdTe (Mercury Cadmium Telluride / MCT) staring arrays for infrared detection do show constant improvements
regarding their compactness and performances. New detectors are now proposed offering system solutions in the
different IR wavebands and profiting of the latest technology improvements as well as MCT performance advantages
and cost reduction.
Among these new detectors, one can find the family of 15 µm pixel pitch detectors including a mid-TV format (384 x
288), a TV format (640 x 512) and a twice-TV format (1280 x 1024). The latest development concerning the mid-TV
format is performed according to very challenging specifications regarding small cost and low power consumption.
These Focal Plane Arrays (FPA) are integrated in dedicated tactical Dewars, taking advantages on last development in
coolers manufacturing and Dewar assembly.
Another development axis at CEA\LETI-LIR and Sofradir concerns the avalanche photodiodes for FPA sensitivity
improvement. This very promising technology is dedicated for low flux applications as active imagery, hyperspectral
applications or small aperture systems.
New development results are presented and future trends are discussed.
HgCdTe (Mercury Cadmium Telluride / MCT) staring arrays for infrared detection do show constant improvements regarding their compactness and performances. New detectors are now proposed offering system solutions in the different IR wavebands and profiting of the latest technology improvements as well as MCT performance advantages and cost reduction. As a matter of fact, the size of MCT wafer has grown to 4", the pixel pitch was lowered to 15μm while maintaining outstanding results on the Focal Plane Arrays (FPA) uniformity. New functions as the Analog to Digital Conversion (ADC) are added to read-out circuits.
Results are presented concerning Non Uniformity Corrections (NUC) stabilities for two Sofradir products. Then results from developments of integrated ADC are addressed and finally, the Jupiter 1280x1024 mid-wave (MWIR) MCT detector performance results are presented.
Sofradir started to work in the field of space applications and especially in the earth observation domain in the beginning
of the 1990th. Thanks to the work done with the support of the French Ministry of Defense and the European Space
Agency, Sofradir has acquired a large know-how and became a major supplier for European space industry.
Nowadays, Sofradir technologies offer possibilities to develop a large panel of high reliable detectors like long linear
arrays or two dimensional arrays covering bandwidth from visible to 15 μm based on qualified Mercury Cadmium
Telluride (MCT) technology. In a near future, latest technology developments will enable to offer new detectors features
in order to simplify instruments designs. In particular, these latest developments concern dual band detectors, increase in
format, pitch reduction and implementation of new functions on the FPA like analogue to digital converter.
This paper proposes an overview of Sofradir technology capabilities for design of custom space detectors. In particular
this paper presents latest technology developments with new results in visible, long wavelength and dual band
technology capabilities. Then, the different approaches for future space FPA are discussed based on examples of
Sofradir started to work in the field of space applications and especially in the earth observation domain in the beginning of the 1990s. Thanks to the work done with the support of the French Ministry of Defence, the European Space Agency, and the CNES, Sofradir has acquired a large know-how and became a major supplier for European space industry. Sofradir space technology is based on the use of a qualified Mercury Cadmium Telluride (MCT) technology hybridized with silicon readout circuit covering a bandwidth from 0.8 to 14 μm. Thanks to this technology Sofradir can answer most of the current space needs in terms of infrared instrument. Future space applications require also an extension of the sensitivity range of the infrared detectors to upper wavelength (typically higher than 15 μm) and to lower wavelength to offer infrared components able to operate both in the visible and short wave infrared range. Physically,
MCT material is able to operate in the visible range and has a potential to offer a high quantum efficiency and large field factor thanks to the hybrid structure. Another issue of future space applications concerns the size and power consumption of the detectors and the associated cryogenic systems. Thanks to its activity, Sofradir has developed very compact cryogenic systems that can be used advantageously for space applications with limited adaptations and qualifications. This paper proposes an overview of Sofradir technology capabilities for space applications with an emphasis on new
potential applications of MCT technology in visible range and for very long wave infrared components. This paper deals also with the capacity of Sofradir MCT and cryogenic technology to be used for both terrestrial and space applications. Finally, a review of the last results obtained in the development of infrared detectors for space applications is proposed.
The infrared (IR) detectors produced in France are using up to date and well mastered technologies based on Mercury Cadmium Telluride (HgCdTe-MCT) material. Based on the maturity of these IR detectors and technologies, IR systems have been produced and are more and more used in different applications including military, security, process
control, environment monitoring, science and space. The produced IR cameras are the so-called second and second and half generations which are very performing but still have some limitation regarding identification, their ability to operate in all weather conditions, and in terms of compactness and reliability. Therefore researches for moving to the next generation (the third one) of cooled detectors
have started to overcome these limitations with the use of bi-color or dual-band as well as to offer more performances. To conduct these researches SOFRADIR and CEA-LETI (LIR) have set up a specific organization, called DEFIR (Design of Excellence for the Future of IR), necessary to increase the efficiency and to reduce the time to production of this new generation. The approach in France regarding the key technologies for the third generation considers the different parameters from the performance to the system cost criteria. Among all the technologies candidates, a new HgCdTe technologies based on molecular beam epitaxy (MBE) have been chosen. Then prototype demonstrations are in progress and confirm the validity of the chosen key technologies.
As a general tendency in the microelectronics field, the miniaturization of the products is more and more important and provides cost and system advantages. Following this general tendency, new InfraRed (IR) staring arrays are more and more compact and offer system solutions in the different IR wavebands. In France, the HgCdTe (Mercury Cadmium Telluride / MCT) material and process, as well as the hybridization technology, have been taken to the next even more advanced level of sophistication to offer these new staring arrays. Thus, for Mid Wave (MW) applications, a 15 μm pitch TV format (640×512) HgCdTe detector, called SCORPIO, is offered with a 1/4W micro cooler with miniaturized cryogenics. This optimized dewar has been extended to TV/4 format, using the successful focal plan array which is in mass production since 2000. Concerning Long Wave array, SOFRADIR has been offering for several years 320×256 LW detectors with a cut-off wavelength tuned between 9μm and 12μm depending on the required application. Based on that experience, two new LW HgCdTe products have been developed in 2004 and are offered since beginning of 2005. Relying on the standard HgCdTe production process with the latest improvements and on the optimized dewar family, VENUS-LW detector is now offered. This is a higher resolution 25μm pitch 384×288 LW IDDCA with a 0.5W micro cooler and with a cutoff between 9μm and 10μm for an operational temperature between 77K and 85K and for a spectral band pass fully satisfying the imagery requirements of compact LW FLIRs. This paper overviews the electro-optical and thermal performances of these three detectors and points out some reliability advantages of this new dewar design. Finally, the development trends for even higher resolution IR detector are discussed.
IR applications are more and more demanding regarding reliability. It is the case of handheld and lightweight UAV applications. To answer these needs, Sofradir and Thales Cryogenics developed a new product family in order to minimize system weight, cost and to increase detector and cooler reliability. Thales Cryogenics has been working on RM integral Stirling cryocoolers since 1995. Then, as a result of several design improvements, it has been possible to increase significantly the efficiency and the reliability of the RM2-Xi cooler over the last 2 years. The RM2-Xi reliability is measured through life time tests which are run continuously on samples taken out from the mass production. Several new tests profiles have been implemented with different climatic and cooler operation conditions. The results gathered enable an accurate evaluation of the cryocooler reliability in the various mission profiles of the customer's applications. Another important performance of an integral cryocooler is efficiency. New mechanical and thermal designs have been implemented. The resulting improvements will be presented and compared with the characteristics of the cryocooler previous version. Based on this new design, Sofradir offers new IR detector products well adapted to handheld and high reliability systems. These new product designs are discussed as well as reliability analysis results.
Sofradir started to work in the field of space applications and especially in the earth observation domain in the beginning of the 1990th. Thanks to the work done with the support of the French Ministry of Defense and the European Space Agency, Sofradir has acquired a large know-how and became a major supplier for European space industry.
Sofradir space technologies offer possibilities to develop a large panel of high reliable detectors like long linear arrays or two dimensional arrays covering bandwidth from 0.8 to 15 μm, answering hyperspectral needs, based on qualified Mercury Cadmium Telluride (MCT) technology. Furthermore, Sofradir has a great experience in the field of packaging and offers complete detectors including dewars and coolers.
This paper proposes an overview of Sofradir technology capabilities for design of custom space detectors for earth observation or hyperspectral applications, covering the field of detection, hybridisation, readout circuit, focal plane structures, packaging and test. Finally, this paper presents the last results obtained in the development of infrared detectors for hyperspectral instruments.
Standard GaAs/AlGaAs QWIPs are now well established for LWIR detection. The main advantage of this technology is the duality with the technology of commercial GaAs devices. The second advantage widely claimed for QWIPs is the so-called band-gap engineering, allowing the custom design of the quantum structure to fulfill the requirements of specific applications such as multispectral detection. QWIPS are close to being optimized. The understanding of detection mechanisms has led to high performance QWIPs working at high temperature (above 77 K). However, as with all quantum detectors, the operating temperature of QWIPs is limited by the thermal current. A new skimmed architecture accommodating this offset has already been demonstrated. The optimization of a skimmed structure requires the modeling procedures and the process, to be adapted. We present the current status of QWIPs in France, including the latest performances achieved with both standard and skimmed architectures. We illustrate the development of our QWIPs by recent results on FPAs.
In the frame of technological preparation for scientific Earth observation programs, the European Space Agency (ESA) has undertaken breadboarding activities dedicated to high resolution thermal radiometer to be implemented on a Low Earth Orbit satellite. Based on the lessons learned during the previous breadboarding phase and taken into account the modification of instrument concept, a LWIR linear focal plane breadboard has been studied and developed for the 11.3 to 12.3 micrometer range. The breadboard is made of two 256 pixels 30 micrometer pitch HgCdTe modules mechanically butted and indirectly hybridized to four multiplexers. Due to image rotation at focal plane level, a linear topology has been selected for pixel arrangement. To achieve the required 0.1 K NEdT, the detector is operated at 55 K. The detector breadboard manufactured and pre characterized by LETI/LIR and SOFRADIR has been integrated in a dedicated test set-up at MMS. First results of the characterization will be presented, with particular emphasis about the dark current and its dispersion as a function of temperature, and the low frequency noise measurements.
The Laboratoire Central de Recherches (LCR) of Thomson Csf and the Societe Francaise de Detecteurs Infrarouge (Sofradir) combined their complementary skills to realize a MultiQuantum Well Infrared Photodetector (QWIP) Focal Plane Array (FPA) sensitive in the long wavelength range of the spectrum (LWIR). Sofradir has industrialized a versatile indium bump hybridization technics qualified for operations as low as 50 K and mostly dedicated to connection of Cadmium Mercury Telluride (CMT) PhotoVoltaic (PV) detectors to silicon Read- Out Integrated Circuits (ROIC). On the other hand, the Thomson Csf/Lcr's QWIP technology based on GaAs/AlGaAs heterostructures is now suitable for industrial development. The device described in this paper is a first generation 144 X 192 MQW staring arrays with a 50 microns pitch; it is operated at temperature as high as 80 K. Such a high operating temperature can be achieved thanks to the optimized design of the QWIP active layer and to the use of a multi purpose experimental CMOS ROIC integrating a current skimming function; this structure developed for high temperature operation of CMT detectors allows for in pixel calibration and derivation of photosite current containing no scene information (e.g. dark and background current) and thus offers enhanced effective storage capacity. In this paper, the main features of the hybrid are given showing the adequacy of this hybridization technics to connecting the QWIP structures. A functional description of the ROIC is presented together with its advantages and limitations in terms of conditions at operating temperature of 70 K and 80 K are thoroughly presented and discussed, in particular in reference with the equivalent CMT performances.
Sofradir has developed many MCT IRFPAs using either the 8 to 12 micron spectral band or the 3 to 5 micron spectral band and using different silicon processor technologies to readout these detector arrays. This paper presents an overview of results coming from different types of arrays, (linear array, TDI array, staring array) using CCD or CMOS readout circuits with different types of signal processors.
For a low cost approach, thermoelectric coolers have often been thought of because of their solid state structure offering low fabrication cost and zero maintenance for cooling down detectors sensitive in the 3 to 5 micrometers spectral band. The performance of such detection assemblies is highly dependent on the achievable cold temperature due to the contribution of dark current in the 200 K operating temperature range. Drawbacks of such an approach reside in the input power required to maintain the detector temperature in adverse environmental temperature conditions. In the aim of evaluating and improving such detectors, Sofradir has established a program leading to the realization of a thermoelectrically cooled detection assembly for field operation, based on its standard 128 X 128 and 288 X 4 IRCCDs. Results are presented here.