1,721,156 research outputs found
Restored vision—augmented vision: arguments for a cybernetic vision
No full textInternational audienceIn this paper, we present some thoughts about the recent developments, made possible by technological advances and miniaturisation of connected visual prostheses, linked to the visual system, operating at different level of this one, on the retina as well as in the visual cortex. While these objects represent a great hope for people with impaired vision to recover partial vision, we show how this technology could also act on the functional vision of well sighted persons to improve or increase their visual performance. In addition to the impact on our cognitive and attentional mechanisms, such an operation when it originates outside the natural real visual field (e.g. cybernetics) raises a number of questions about the development and use of such implants or prostheses in the future.Nous présentons dans ce compte rendu quelques réflexions liées aux développements récents, rendus possible grâce aux progrès technologiques et à la miniaturisation, de prothèses visuelles connectées, liées au système visuel et pouvant intervenir à différents endroits de celui-ci, aussi bien sur la rétine qu'au niveau du cortex visuel. Si ces objets constituent un grand espoir, pour les personnes mal, ou non-voyantes, de pouvoir récupérer une vision partielle, on montre comment cette technologie pourrait également agir sur la vision fonctionnelle de bien-voyants afin d'en améliorer ou augmenter les performances. Outre l'impact sur nos mécanismes cognitifs et attentionnels, une telle intervention lorsqu'elle trouve son origine hors du champ visuel naturel (par exemple cybernétique) pose un certain nombre de questions sur le développement et l'utilisation de tels implants ou prothèses dans le futur
Safe and ergonomic welding masks by fast liquid crystals
No full textInternational audienceRecent developments in welding technology, in particular the high intensity pulsed welding arc, have sharpened the requirements on speed and adjustable attenuation for safe and ergonomic operations. With this advent the conventional welding helmets based on nematic liquid crystals are facing difficulties because the nematics are not responding fast enough to stroboscopically follow the changing intensity of the arc during pulsed welding. We propose here a new generation of welding shutters based on smectic ferroelectric or antiferroelectric) liquid crystals which are fast enough to be synchronized to follow pulsed arc regimes and hence permitting a better visibility of the object under work. The two varieties of smectic materials used are polymer-stabilized in order to make the device shock-proof to prevent the formation of specific defects such as stripes and chevrons, and to reduce the back-relaxation time in the antiferroelectric case
Large tilt smectic C* liquid crystal for polarizorless phase modulation
No full textInternational audience
Dispositif à transmission de lumière variable à base de cristal liquide dichroïque
No full textDate de dépôt : 22/05/2014N° de dépôt : PCT/EP201406051
Large tilt smectic C* liquid crystal for polarizorless phase modulation
No full textInternational audience
Node-based reconfigurable volume interconnects - Part 1 : principles and optical implementations
No full textInternational audience
Potential uses of the Fourier plane in free-space wavelength demultiplexing systems
No full textInternational audienceWe study the possibility of introducing programmable filters in the Fourier plane of an optical free-space wavelength demultiplexer to provide wavelength-band selection or programmable optical add and drop multiplexing. Various 4f configurations are modeled, and we compare the respective advantage of two main cases: the first where the dispersive element is superimposed in the Fourier plane with a programmable transmittance, the second where the dispersive element is combined with the lens(es) and the Fourier plane is free to set the programmable element. An analytical model of the beam propagation is proposed in the case of a Gaussian beam to make easier the choice of adjustable parameters and optical configurations. The potential use of the Fourier plane free configurations is assessed in terms of wavelength-band resolution, selectivity, and attenuation dynamic range
Safe and ergonomic welding masks by fast liquid crystals
No full textInternational audienceRecent developments in welding technology, in particular the high intensity pulsed welding arc, have sharpened the requirements on speed and adjustable attenuation for safe and ergonomic operations. With this advent the conventional welding helmets based on nematic liquid crystals are facing difficulties because the nematics are not responding fast enough to stroboscopically follow the changing intensity of the arc during pulsed welding. We propose here a new generation of welding shutters based on smectic ferroelectric or antiferroelectric) liquid crystals which are fast enough to be synchronized to follow pulsed arc regimes and hence permitting a better visibility of the object under work. The two varieties of smectic materials used are polymer-stabilized in order to make the device shock-proof to prevent the formation of specific defects such as stripes and chevrons, and to reduce the back-relaxation time in the antiferroelectric case
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