666 research outputs found

    ImplementaciĂł d'un entorn virtual per a la realitzaciĂł de prĂ ctiques de la unitat formativa “Instal·lacions hidrĂ uliques i pneumĂ tiques” del CFGS d'AutomociĂł

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    MotivaciĂł: Actualment el departament d’AutomociĂł disposa de dos panells pneumĂ tics marca FESTO per portar a terme les prĂ ctiques de la unitat formativa UF1 Instal·lacions pneumĂ tiques i hidrĂ uliques del mĂČdul formatiu “Sistemes de transmissiĂł de forces i trens de rodatge” del cicle de grau superior d’AutomociĂł. El nombre d’alumnes que cursen aquest cicle Ă©s aproximadament de setze estudiants, fet que comporta que aquest material resulti limitat pel desenvolupament de la part prĂ ctica del currĂ­culum de la unitat. Objectius: Aquest fet, afegit a l’actual situaciĂł econĂČmica global, proposa buscar altres alternatives adients que permetin desenvolupar les prĂ ctiques de manera sostenible obtenint els mateixos resultats d’aprenentatge. SoluciĂł proposada: En sintonia amb l’evoluciĂł tecnolĂČgica actual, on la tendĂšncia Ă©s el control de processos i instal·lacions mitjançant l’ordinador, es proposa la utilitzaciĂł de les TIC com a eina on portar a terme la simulaciĂł de les prĂ ctiques. Aquest material permet entendre el mĂłn real a travĂ©s d’una eina virtual, i establir les semblances i diferĂšncies entre la simulaciĂł i la realitat, al contrastar els resultats obtinguts amb les prĂ ctiques al taller. S’incorpora aixĂ­ un entorn d’aprenentatge nou i enriquidor per l’alumne, que amb molta probabilitat es trobarĂ  quan s’introdueixi en el mĂłn laboral. En aquest treball es desenvolupa material didĂ ctic per a cinc sessions de prĂ ctiques de tres hores cadascuna, utilitzant un programari de simulaciĂł pneumĂ tica anomenat Fluidsim, i dos panells pneumĂ tics existents al taller. AixĂ­ mateix es proposa una metodologia de treball que evita el solapament dels equips materials, assegura que cada alumne realitzi com a mĂ­nim una prĂ ctica sobre panell, i al mateix temps no se’n repeteixi cap. Aquesta metodologia facilita la tasca del docent i l’avaluaciĂł de la unitat formativa

    Comparison of peristrophic multiplexing and a combination of angular and peristrophic holographic multiplexing in a thick PVA/acrylamide photopolymer for data storage

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    Two different types of multiplexing are used to store 90 holograms at the same location in a polyvinyl alcoholacrylamide photopolymer material. In the first, the 90 holograms are stored using only peristrophic multiplexing, whereas in the second a combination of angular and peristrophic multiplexing is used. The results (diffraction efficiency and dynamic range, M#) obtained with these two multiplexing techniques are compared. With the first, the dynamic range was M# = 13 and with the second M# = 8. An exposure schedule method is used to calculate the exposure time necessary to store the holograms with a more uniform, higher diffraction efficiency.This work was supported by the “Ministerio de Educación y Ciencia (Spain)” under projects FIS2005-05881-C02-01 and FIS2005-05881-C02-02, and by the “Generalitat Valenciana” under Project GV06/172

    Experimental Conditions to Obtain Photopolymerization Induced Phase Separation Process in Liquid Crystal-Photopolymer Composite Materials under Laser Exposure

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    We analyze the experimental conditions necessary to obtain a photopolymerization induced phase separation process inside liquid crystal-photopolymer composite materials. Composites stored for 24 hours perform poorly in hologram recording but a good result is obtained if they are used recently prepared. We use a procedure combining heat and sonication to disarrange the liquid crystal structures formed during storage of the composite. We also propose incoherent light treatment after recording the hologram in order to evaluate if the phase separation evolved correctly during hologram recording.The work was supported by the “Ministerio de Economía y Competitividad” of Spain under Projects FIS2011-29803-C02-01 and FIS2011-29803-C02-02 and by the “Generalitat Valenciana” of Spain under Projects PROMETEO/2011/021 and ISIC/2012/013

    Blazed Gratings Recorded in Absorbent Photopolymers

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    Phase diffractive optical elements, which have many interesting applications, are usually fabricated using a photoresist. In this paper, they were made using a hybrid optic-digital system and a photopolymer as recording medium. We analyzed the characteristics of the input and recording light and then simulated the generation of blazed gratings with different spatial periods in different types of photopolymers using a diffusion model. Finally, we analyzed the output and diffraction efficiencies of the 0 and 1st order so as to compare the simulated values with those measured experimentally. We evaluated the effects of index matching in a standard PVA/AA photopolymer, and in a variation of Biophotopol, a more biocompatible photopolymer. Diffraction efficiencies near 70%, for a wavelength of 633 nm, were achieved for periods longer than 300 ”m in this kind of materials.This work was supported by the “Ministerio de EconomĂ­a y Competitividad” (projects FIS2014-56100-C2-1-P and FIS2015-66570-P) and by the “Generalitat Valenciana” of Spain (projects PROMETEOII/2015/015 and ISIC/2012/013)

    Registro de redes diente de sierra en fotopolĂ­meros: efecto del sellante

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    Los fotopolĂ­meros son unos materiales fotosensibles interesantes para el registro de elementos Ăłpticos difractivos. No obstante el registro de perfiles de fase abruptos, como las redes de diente de sierra, presenta problemas por los rĂĄpidos cambios que tienen lugar en la superficie de estos materiales. En este trabajo se propone la utilizaciĂłn de sellantes con un Ă­ndice de refracciĂłn promedio del fotopolĂ­mero para mejorar el registro de elementos difractivos abruptos.Financiado por Ministerio de EconomĂ­a y Competitividad (FIS2011-29803-C02-01 y FIS2011-29803-C02-02), Generalitat Valenciana (PROMETEO/2011/021, ISIC/2012/013 y GV/2014/076), y Universidad de Alicante (GRE12-14)

    Split-field finite-difference time-domain method for second-harmonic generation in two-dimensionally periodic structures

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    The split-field finite-difference time-domain method is extended to second-harmonic generation in two-dimensionally periodic structures. Making use of the full coefficient-tensor formalism, a coupled nonlinear system of equations, which must be solved at each update of the electromagnetic field, is developed. The accuracy of the method is verified by comparing the results to well-known one-dimensional problems. The results for L-shaped arrays are compared with results obtained with the Fourier modal method.This work is partially supported by the “Ministerio de Economía y Competitividad” of Spain under project FIS2011-29803-C02-01; by the “Generalitat Valenciana” of Spain under projects PROMETEO/2011/021, ISIC/2012/013, and GV/2014/076; and by the “Universidad de Alicante” of Spain under project GRE12-14

    Photopolymer characterization for diffractive and holographic applications

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    The work was supported by the “Ministerio de Economía y Competitividad” of Spain under projects FIS2011-29803-C02-01 and FIS2011-29803-C02-02 and by the “Generalitat Valenciana” of Spain under projects PROMETEO/2011/021 and ISIC/2012/013

    Accurate control of a liquid-crystal display to produce a homogenized Fourier transform for holographic memories

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    We show an accurate procedure to obtain a Fourier transform (FT) with no dc term using a commercial twisted-nematic liquid-crystal display. We focus on the application to holographic storage of binary data pages, where a drastic decrease of the dc term in the FT is highly desirable. Two different codification schemes are considered: binary π radians phase modulation and hybrid ternary modulation. Any deviation in the values of the amplitude and phase shift generates the appearance of a strong dc term. Experimental results confirm that the calculated configurations provide a FT with no dc term, thus showing the effectiveness of the proposal.This work was supported by the “Ministerio de EducaciĂłn y Ciencia (Spain)” under projects FIS2005-05881-C02-01 and FIS2005-05881-C02-02, and by the “Generalitat Valenciana” under Project GV06/007

    Novel characterization methods and applications for photopolymers

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    Este trabajo ha sido financiado por el Ministerio de EconomĂ­a y Competitividad (FIS2011-29803-C02-01 y FIS2011-29803-C02-02), por la Generalitat Valenciana (PROMETEO/2011/021, ISIC/2012/013) y por la Universidad de Alicante (GRE12-14)

    Complex diffractive optical elements stored in photopolymers

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    Photopolymers have been used mainly for holographic recording applications. Nowadays, the improvements made in diffusion models, simulating phase image stored in these materials, enable a wide range of complex diffractive optical elements (DOEs) to be fabricated. Concurrently, the miniaturization of spatial light modulators makes it possible to generate both symmetric and non-symmetric DOEs. We show the procedure to record different complex diffractive elements, and we study the viability to fabricate them based on photopolymers. In particular we evaluate the recording of achromatic lenses, axicons and fork gratings interesting to obtain optical vortices. To achieve this goal, we use a three-dimensional diffusion model, previously experimentally validated with the recording of diffractive lenses.Ministerio de EconomĂ­a y Competitividad (Spain) FIS2017-82919-R (MINECO/AEI/FEDER, UE) and FIS2015-66570-P(MINECO/ FEDER); Generalitat Valenciana (Spain) (PROMETEO II/2015/015)
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