Publications (11)0 Total impact
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Conference Proceeding: Dynamic polarimetric imaging: overview and implementation using liquid crystal cells
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ABSTRACT: This paper describes the implementation of an imaging polarimeter using a single ferroelectric liquid crystal light modulator. It provides partial Stokes information at 234 Hz, much faster than polarimeters using nematic liquid crystal light modulators.Euro-American Workshop on Information Optics, Annecy (France); 01/2008 -
Article: High-speed degree-of-polarization imaging with a ferroelectric liquid-crystal modulator
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ABSTRACT: Images describing polarimetric characteristics of objects are more and more used when studying complex scenes. In some cases, only the depolarization phenomenon, mostly due to scattering, proves of interest and estimating the degree of polarization (DOP) is sufficient. For a linearly polarized beam under normal incidence, when the materials in the scene exhibit neither birefringence nor dichroism, this comes down to an intensity measurement in two crossed directions. Nevertheless, the classical optical setup, consisting mainly of a rotating polarizer used as a polarization state analyzer, gives good-quality images, but cannot provide dynamic information. In this paper, we propose to use a ferroelectric liquid-crystal modulator in an imaging polarimeter. We demonstrate the use of this modulator as a polarization state analyzer for frame rates up to about 400 Hz. Provided a fast camera is used, we show that the polarimeter allows us to surpass the classical video frame rate. We proposea setup using a rapid CCD camera (up to 233 Hz). Images in DOP are of very high quality and hold their own against images obtained with a classical polarizer. With a faster camera, we were able to obtain images at up to 400 Hz.Optical Engineering. 01/2008; 47(3):033201. -
Article: High speed partial Stokes imaging using a ferroelectric liquid crystal modulator
J. European Optical Society. 01/2008; -
Conference Proceeding: Spatial Light Modulators For Information Processing: Applications And Overview
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ABSTRACT: We present the characterization of a ferro-electric liquid crystal spatial light modulator and of a nematic liquid crystal spatial light modulator. It is shown that the nematic device can be compensated for its phase distortions and a method is proposed for increasing its frame rate while maintaining a maximum phase modulation of 2π. Several applications in information processing are presented with experimental results.Sixth Euro American Workshop on Information Optics, Reykjavik (Islande); 01/2007 -
Article: Pilosimètre et profilomètre pour matériaux fibreux souples
Contrôles-Essais-Mesures. 01/2007; supplément au numéro d'octobre 2007. -
Conference Proceeding: High speed linear polarization evaluation with a single light modulator
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ABSTRACT: This paper describes the implementation of an imaging polarimeter using a single ferroelectric liquid crystal light modulator. It provides partial Stokes information at 234 Hz, much faster than polarimeters using nematic liquid crystal light modulators.3rd topical meeting on Advanced Imaging Techniques, Lille; 01/2007 -
Conference Proceeding: Mise en oeuvre d'un polarimètre rapide à l'aide d'un modulateur à cristaux liquides ferroélectriques
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ABSTRACT: L'imagerie de polarisation permet d'obtenir des informations sur l'observation de scènes complexes, par exemple à travers l'évaluation du degré de polarisation. Les montages classiques utilisent un polariseur tournant ou un modulateur à cristaux liquides nématiques comme analyseur d'état de polarisation. Dans cette étude, nous mettons en place un polarimètre imageant utilisant un modulateur spatial de lumière à cristaux liquides ferroélectriques pouvant atteindre une fréquence de 1000 Hz. De fait, notre polarimètre permet de dépasser la classique limite de 50 Hz, avec une caméra assez rapide. Notre polarimètre est comparé avec les systèmes classiques à polariseur tournant.Septième colloque international francophone Méthodes et Techniques Optiques pour l'Industrie, Mulhouse; 01/2006 -
Conference Proceeding: Pilosimètre et profilomètre pour matériaux fibreux souples
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ABSTRACT: Nous présentons un dispositif de mesure optique destiné à l’étude des états de surface des matériaux textiles. Suivant les post-traitements de signal et d’image appliqués, il fonctionne soit en pilosimètre, permettant de déterminer finement les caractéristiques de la pilosité émergeant de la surface, soit en profilomètre.Septième colloque international francophone Méthodes et Techniques Optiques pour l'Industrie, Mulhouse; 01/2006 -
Conference Proceeding: Implementation of a high-speed imaging polarimeter using a liquid crystal ferroelectric modulator
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ABSTRACT: Imaging polarimetry through evaluation of the degree of polarization of light can give much information about complex scenes. A classic optical set-up usually consists in using a rotating polarizer or a tunable phase modulator as a polarization state analyzer. In this study, we implement an imaging polarimeter using a ferroelectric liquid crystal spatial light modulator as a polarization state analyzer able to run at 1000 Hz. This way, our polarimeter can overcome the classic limit of 50 Hz, provided that the camera is fast enough. Our polarimeter is compared with classical systems which use rotating polarizers.Optical Sensing II, Strasbourg; 01/2006 -
Conference Proceeding: Optical characterization of the touch of fibrous materials
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ABSTRACT: Various optical devices were conceived and implemented at University de Haute Alsace in order to identify and characterize parameters linked to the roughness and to the hairiness of fibrous surfaces (textile fabrics or nonwovens). A roughness meter consisting in measuring the reflection of a thin line was developped. This technique essentially measures the fabric-reflected rays in all surface directions, because the fabric is rotated in its plane during the measurement. A Fourier temporal analysis of the reflected beam scanned across the fabric surface allows the fabric structure periods to be determined, because these periods yield peaks in the frequency spectrum. An improved version able to measure in line (the optical apparatus rotates over a fixed sample) was developped and can also be used as an extensometer. A hairiness meter based on Fourier spatial filtering was implemented: this edge extraction method separates hairiness and structural information. This technique operates at the speed of light. Improving the set-up with the adjunction of a camera and a digital post-processing allows the user to obtain the distribution of hair length. The two devices are complementary and allow the processes that modify the fabric surface to be understood and controlled.First International Workshop Materials and Sensations, Pau; 01/2004 -
Conference Proceeding: Caractérisation de modulateurs spatiaux de lumière
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ABSTRACT: L'utilisation de modulateurs spatiaux de lumière (SLM) est aujourd'hui largement répandue. Les SLM sont présents au niveau grand public dans les vidéoprojecteurs et au niveau professionnel où ils sont utilisés pour la projection de frange, l'optique diffractive et la corrélation optique. Les SLM sont assimilables à des "diapositives reconfigurables". Ils permettent d'afficher des images sur plusieurs niveaux de gris, en amplitude et/ou en phase. Devant la variété des SLM disponibles sur le marché, il est devenu nécessaire de les caractériser. Nous proposons une technique rapide et indépendante de la structure du SLM considéré.Contrôles et Mesures Optiques pour l'Industrie, Saint-Etienne; 01/2004
