The purpose of this theoretical study carried out under CNES contract is to analyze the feasibility of small space debris detection and classification with an optical sensor on-board micro-satellite. Technical solutions based on active and passive sensors are analyzed and compared. For the most appropriated concept an optimization was made and theoretical performances in terms of number of detection versus class of diameter were calculated. Finally we give some preliminary physical sensor features to illustrate the concept (weight, volume, consumption,…).
Sofradir IR detectors are being deployed in a lengthening line of space applications (earth observation, atmospheric observation, scientific missions, etc…), and also in the whole range of tactical applications (portable cameras, missile seekers, land, airborne and naval systems, etc…). Sofradir is taking advantage of these two areas. Firstly, space applications are developing new advances and technologies that can later be introduced in the production of IR detectors for tactical applications, thereby increasing their quality and reliability. In addition, Sofradir can better satisfy space application requirements for failure rates, as these can only be demonstrated with the large number of detectors manufactured, which tactical applications provide. As a result, this approach offers a continuous cycle for reliability of IR detectors, accelerating reliability growth in production, and at the same time meeting requirements for space applications. This paper presents recent improvements introduced in production lines of HgCdTe detectors, that increase performances, image quality, and reliability.
Sofradir IR detectors are being deployed in a lengthening line of space applications (earth observation,
atmospheric observation, scientific missions, etc...).
At first glance, one may ask what do detectors for space applications have in common with detectors for tactical
applications? On the one hand, space applications require far fewer quantities and IR detector reliability and
electro-optical performances must be exceptionally high. Tactical applications, on the other hand, look to
quantities in the thousands per year, delivered at low cost. As opposed to focusing on the differences, Sofradir is
taking advantage of these two areas. Firstly, space applications are developing new advances and technologies that
can later be introduced in the production of IR detectors for tactical applications, thereby increasing their quality
and reliability. In addition, Sofradir can better satisfy space application requirements for failure rates, as these can
only be demonstrated with the large number of detectors manufactured, which tactical applications provide. This
advantage is only possible because the core of the technologies and manufacturing processes are common to both
applications. As a result, this approach offers a continuous cycle for reliability of IR detectors, accelerating
reliability growth in production, and at the same time meeting requirements for space applications.
Tactical applications are very sensitive to maintenance periodicity and in lot of cases, maintenance position is
critical regarding mission availability. Moreover, maintenance has a cost that becomes quickly prohibitive when
the cooler or the vacuum have to be repaired too often.
Sofradir has worked a lot during last years on reliability and life cycle cost optimization considering all the IR
detectors subassemblies. This work has lead to an increased robustness of detectors and technologies even under
severe environmental conditions, and reduced variabilities in production. This paper presents the state of the art of
Integrated Detector Dewar Cooler Assembly (IDDCA)'s reliability, the production means and the methods that
allow us today to propose detectors with very high reliability without maintenance. These detectors are a
breakthrough for life cycle cost for tactical applications as portable cameras, airborne systems, and missiles.
Environmental conditions (thermal, vibrations and shocks) are key performance and reliability factors for designing IR detectors. To address these constraints Sofradir has developed specific concepts to make the IR detector more robust in stringent environmental conditions. This paper describes these design concepts that involve both the IRFPA (IR Focal Plane Array) and the cryogenics part, as well as the level of robustness that is achieved.
Infrared (IR) applications are more and more demanding regarding reliability and cost. Moreover contracts are
getting further than simple cost acquisition considerations, asking for life cycle cost requirements. Life cycle cost
approach is the way to combine increase of reliability with reduction of costs. Starting from the design of a IR
detector and taking in consideration some specific tactical system constraints, the whole cost and reliability
analyses have to be made including maintenance approaches. The key parameters for the detectors are the thermal
cycles behaviour, the cooler reliability and the vacuum behaviour.
Based on Sofradir experience of life cycle cost contracts and on IR staring arrays results, this paper discuss the
optimization of life cycle cost and reliability as well as future trends regarding IR detectors and reduction of life
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.
TV/4 format (320×256) detectors are today the most produced. They have demonstrated high thermal performance and are cost effective at the mass production level. However, in response to system requirements of very high resolution, miniaturization and cost reduction, SOFRADIR is now offering full TV format (640x512) detectors with graduated levels of performances regarding pitch size and cryogenics. In particular a TV format with 15 μm pitch is offered allowing the integration of highly miniaturized cryogenics dedicated to compact systems or, depending of the applications, the upgrade of existing systems by using the same miniature cryogenics as the ones used for TV/4 format. Regarding TV format (640x512) with 15μm pitch, technological adaptations were validated at CEA-LETI/LIR (France) at the beginning of 2002. With respect to the 20μm pitch TV formats whose purpose is to offer high resolution performances in slightly modified cryogenics, this new 15μm pitch MCT TV format exhibits even higher performances in very small size optimized cryogenics in order to fit the system requirements of miniaturization and cost reduction and to achieve a cost effective production level. In this way, this 15μm pitch 640x512 MWIR MCT detectors will become, in the coming years, the most affordable large format at production level.