Properties of PVA/AA photopolymers at very low spatial frequencies
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|Title:||Properties of PVA/AA photopolymers at very low spatial frequencies|
|Authors:||Gallego, Sergi | Márquez, Andrés | Méndez Alcaraz, David Israel | Marini, Stephan | Fernandez-Varo, Helena|
|Research Group/s:||Holografía y Procesado Óptico|
|Center, Department or Service:||Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal | Universidad de Alicante. Departamento de Óptica, Farmacología y Anatomía | Universidad de Alicante. Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías|
|Keywords:||Diffractive elements | Photopolymers | Low frequencies|
|Knowledge Area:||Física Aplicada | Óptica|
|Publisher:||SPIE, The International Society for Optical Engineering|
|Citation:||GALLEGO RICO, Sergi, et al. "Properties of PVA/AA photopolymers at very low spatial frequencies". En: Holography: Advances and Modern Trends: 18 June 2009, Prague, Czech / edited by Miroslav Miler, Miroslav Hrabovský. Bellingham, Wash. : SPIE, 2009. (Proceedings of SPIE; Vol. 7358). ISBN 978-0-81947-632-6, pp. 73581G-1/9|
|Abstract:||Polyvinyl/acrylamide (PVA/AA) photopolymers are often used as holographic recording materials. Depending on each particular application, different spatial frequencies can be recorded. The only limitation appears when high spatial frequencies are stored (over 2500 lines/mm the diffraction efficiencies achieved are very low). This cut-off spatial frequency is due to the finite size of polymer chains. On the other hand, in the case of very low spatial frequencies, monomer diffusion times are highly increased and so there are important distortions in the shape of the gratings stored. In order to characterize the hologram formation in these types of materials, many parameters must be taken into account. One of the most important parameters to measure is the diffusion of the molecules inside the layer. In this sense, when very low spatial frequencies are recorded, component diffusion and thickness variations can be determined more accurately. In previous works, we have characterized the photopolymer at the zero spatial frequency limit, where diffusion does not take place, measuring the refractive index variations and the shrinkage. In this work we have recorded different long period gratings (at very low spatial frequencies diffusion starts to be important) and we have analyzed the profiles formed in the material during exposure and the refractive index distributions. This study has been carried out measuring the transmission and reflection orders of diffractive gratings. Furthermore, to obtain a deeper insight into the profile of the gratings recorded and especially into the sharpness of their edges, we have obtained numerically the diffraction-efficiency values fitting a Fermi-Dirac function to each profile.|
|Sponsor:||This work was supported by the “Ministerio de Edicación y Ciencia” (Spain) under projects FIS2008-05856-C02-01 and FIS2008-05856-C02-02 and by Generalitat Valenciana under project GVPRE/2008/137.|
|Rights:||Copyright 2009 Society of Photo-Optical Instrumentation Engineers. This paper was published in Proceedings of SPIE, vol. 7358, and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.|
|Appears in Collections:||INV - GHPO - Artículos de Revistas|
INV - GHPO - Comunicaciones a Congresos, Conferencias, etc.
INV - GMECA - Comunicaciones a Congresos, Conferencias, etc.
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