Overview of CMOS process and design options for image sensor dedicated to space applications

With the growth of huge volume markets (mobile phones, digital cameras…) CMOS technologies for image sensor improve significantly. New process flows appear in order to optimize some parameters such as quantum efficiency, dark current, and conversion gain. Space applications can of course benefit from these improvements. To illustrate this evolution, this paper reports results from three technologies that have been evaluated with test vehicles composed of several sub arrays designed with some space applications as target. These three technologies are CMOS standard, improved and sensor optimized process in 0.35µm generation. Measurements are focussed on quantum efficiency, dark current, conversion gain and noise. Other measurements such as Modulation Transfer Function (MTF) and crosstalk are depicted in [1]. A comparison between results has been done and three categories of CMOS process for image sensors have been listed. Radiation tolerance has been also studied for the CMOS improved process in the way of hardening the imager by design. Results at 4, 15, 25 and 50 krad prove a good ionizing dose radiation tolerance applying specific techniques

Contest Theory and its Applications in Sports

This paper outlines how the theory of contests is applied to professional team sports leagues. In the first part, we present the traditional Tullock contest and explain some basic properties of the equilibrium. We will then extend this static contest to a two-period model in order to analyze dynamic aspects of contests. In the second part, we will present applications of contest theory in sports. In particular, we will show how the Tullock framework is applied to models of team sports leagues. For this purpose, we will first explain the value creation process in team sports leagues and show how club revenues are related to the contest success function. Then, we present some basic modeling issues; for instance, we show how the assumption of flexible vs. fixed talent supply depends on the league under consideration and how it influences the equilibria. Furthermore, we explicate the effect of revenue sharing on competitive balance in the different models. Then we address the relationship between competitive balance and social welfare. Finally, we illustrate why many clubs tend to "overinvest" in playing talent in many team sports leagues.Contest theory, Tullock contest, sports leagues, competitive balance, revenue sharing, social welfare, overinvestment

Space optical instruments optimisation thanks to CMOS image sensor technology

Today, both CCD and CMOS sensors can be envisaged for nearly all visible sensors and instruments designed for space needs. Indeed, detectors built with both technologies allow excellent electro-optics performances to be reached, the selection of the most adequate device being driven by their functional and technological features and limits. The first part of the paper presents electro-optics characterisation results of CMOS Image Sensors (CIS) built with an optimised CMOS process, demonstrating the large improvements of CIS electro-optics performances. The second part reviews the advantages of CMOS technology for space applications, illustrated by examples of CIS developments performed by EADS Astrium and Supaéro/CIMI for current and short term coming space programs

CMOS detectors for space applications: from R&D to operational program with large volume foundry

Nowadays, CMOS image sensors are widely considered for space applications. The use of CIS (CMOS Image sensor) processes has significantly enhanced their performances such as dark current, quantum efficiency and conversion gain. However, in order to fulfil specific space mission requirements, dedicated research and development work has to be performed to address specific detector performance issues. This is especially the case for dynamic range improvement through output voltage swing optimisation, control of conversion gain and noise reduction. These issues have been addressed in a 0.35μm CIS process, based on a large volume CMOS foundry, by several joint ISAE- EADS Astrium R&D programs. These results have been applied to the development of the visible and near-infrared multi-linear imager for the SENTINEL 2 mission (LEO Earth observation mission for the Global Measurement Environment and Security program). For this high performance multi-linear device, output voltage swing improvement is achieved by process optimisation done in collaboration with foundry. Conversion gain control is also achieved for each spectral band by managing photodiode capacitance. A low noise level at sensor output is reached by the use of an architecture allowing Correlated Double Sampling readout in order to eliminate reset noise (KTC noise). KTC noise elimination reveals noisy pixels due to RTS noise. Optimisation of transistors’s dimensions, taking into account conversion gain constraints, is done to minimise these noisy pixels. Additional features have been also designed: 1) Due to different integration times between spectral bands required by mission, a specific readout mode was developed in order to avoid electrical perturbations during the integration time and readout. This readout mode leads to specific power supply architecture. 2)Post processing steps can be achieved by alignment marks design allowing a very good accuracy. These alignment marks can be used for a black coating deposition between spectral bands (pixel line) in order to minimise straight lighteffects. In conclusion a review of design improvements and performances of the final component is performed

High performances monolithic CMOS detectors for space applications

During the last 10 years, research about CMOS image sensors (also called APS -Active Pixel Sensors) has been intensively carried out, in order to offer an alternative to CCDs as image sensors. This is particularly the case for space applications as CMOS image sensors feature characteristics which are obviously of interest for flight hardware: parallel or semi-parallel architecture, on chip control and processing electronics, low power dissipation, high level ofradiation tolerance... Many image sensor companies, institutes and laboratories have demonstrated the compatibility of CMOS image sensors with consumer applications: micro-cameras, video-conferencing, digital-still cameras. And recent designs have shown that APS is getting closer to the CCD in terms ofperformance level. However, the large majority ofthe existing products do not offer the specific features which are required for many space applications. ASTRI1JM and SUPAERO/CIMI have decided to work together in view of developing CMOS image sensors dedicated to space business. After a brief presentation of the team organisation for space image sensor design and production, the latest results of a high performances 512x512 pixels CMOS device characterisation are presented with emphasis on the achieved electro-optical performance. Finally, the on going and short-term coming activities of the team are discussed

Development of high-performances monolithic CMOS detectors for space applications

This paper describes the development of a 750x750 pixels CMOS image sensor for star tracker applications. A first demonstrator of such a star tracker called SSM star tracker built around a 512x512 detector has been recently developed and proves the feasibility of such instrument. In order to take fully advantage of the CMOS image sensor step, the 750x750 device called SSM CMOS detector which will take part of the final star tracker, can be considered as a major technical breakthrough that gives a decisive advantage in terms of on satellite implementation cost and flexibility (sensor mass and power consumption minimisation, electronics and architecture flexibility). Indeed, built using the 0.5μm Alcatel Microelectronics standard CMOS technology, the SSM CMOS detector will feature on-chip temperature sensor and on-chip sequencer. In order to evaluate the radiation tolerance of such manufacturing technology, a radiation campaign that contains studies of total dose and latch-up effects has been led on a specific test vehicle

Research-grade CMOS image sensors for remote sensing applications

Imaging detectors are key elements for optical instruments and sensors on board space missions dedicated to Earth observation (high resolution imaging, atmosphere spectroscopy...), Solar System exploration (micro cameras, guidance for autonomous vehicle...) and Universe observation (space telescope focal planes, guiding sensors...). This market has been dominated by CCD technology for long. Since the mid-90s, CMOS Image Sensors (CIS) have been competing with CCDs for consumer domains (webcams, cell phones, digital cameras...). Featuring significant advantages over CCD sensors for space applications (lower power consumption, smaller system size, better radiations behaviour...), CMOS technology is also expanding in this field, justifying specific R&D and development programs funded by national and European space agencies (mainly CNES, DGA and ESA). All along the 90s and thanks to their increasingly improving performances, CIS have started to be successfully used for more and more demanding space applications, from vision and control functions requiring low-level performances to guidance applications requiring medium-level performances. Recent technology improvements have made possible the manufacturing of research-grade CIS that are able to compete with CCDs in the high-performances arena. After an introduction outlining the growing interest of optical instruments designers for CMOS image sensors, this paper will present the existing and foreseen ways to reach high-level electro-optics performances for CIS. The developments and performances of CIS prototypes built using an imaging CMOS process will be presented in the corresponding section

Ma femme est mon risk manager : le rôle de la femme de l'entrepreneur dans le management de la santé et sécurité au travail

Cet article fait état d'une étude qualitative à caractère monographique qui étudie le rôle de la femme d'un dirigeant de petite entreprise dans la gestion des risques liés à la santé et à la sécurité au travail. Dans un contexte spécifique de relations sociales faiblement polarisées qui caractérisent la petite entreprise, le dirigeant a souvent du mal à se positionner pour déployer un plan de prévention des risques. Cette étude menée dans une entreprise française de moins de 50 salariés a pour ambition de suivre dans la durée le processus qui va de l'information du chef d'entreprise sur ses obligations réglementaires jusqu'à l'opérationnalisation de la prévention des risques sur le terrain. En effet, si les actions de sensibilisation du chef d'entreprise à ses obligations réglementaires ont été bien documentées, on sait peu de choses sur la pérennisation de ces dernières. Conduite dans le secteur de la construction, secteur particulièrement accidentogène, cette étude met donc en évidence les moyens déployés par l'épouse du dirigeant pour conduire sa mission et les difficultés organisationnelles et symboliques auxquelles elle se heurte. Dans une démarche de recherche intervention, où le chercheur implémente des outils de gestion et coproduit les connaissances avec les acteurs de l'entreprise au cours de l'intervention, cette étude permet de mettre à jour les mécanismes à l'œuvre de résistance au changement et les limites de l'engagement de la conjointe du dirigeant sur ces questions

Nuclear Decommissioning and Organisational Reliability: Involving Subcontractors in Collective Action

International audienceThe concept of organisational reliability is at the heart of the safety of at-risk systems. Many studies have been conducted in the nuclear industry; all emphasise the study of plants in normal, daily operation or during shutdowns. However, decommissioning, whether ongoing or planned, places a sharp focus on the question. This is because, on the one hand operating companies make significant changes to their organisation to meet the challenges and requirements of decommissioning, on the other they must subcontract a large number of tasks related to the decommissioning. The use of subcontractors is not new; in the nuclear industry it became widespread in the 1990s and now represents more than 80% of activity. However, the specificities of decommissioning lead to a re-examination of the overall organisation and the conclusion that subcontractors are a key player in its success

An experimental preventive action for SMEs: A Trojan horse for a cross-learning scheme

International audienceAs regards Occupational Health and Safety (OHS), Small and Medium Sized Enterprises (SMEs) are hard to reach by the health and safety inspection.. Among the remarkable actions which have been implemented in France, information meetings made for every branch of industry can be taken as an example. All these supports have increased the level of awareness of the OHS issue in SMEs but have also reached their limits in terms of effective assistance and generalization. This paper therefore aims at presenting a collective preventive action which involved a research laboratory, a chamber of commerce, OHS advisors as well as the labour inspectorate. This pilot action designed for managers-owners of small businesses under 50 employees allowed volunteers to asses their level of compliance with OHS regulations thanks to a software tool. At the end of this action a qualitative survey has been carried out to asses the relevance of this experimentation