Papers by Luis Carretero Lopez
Se ha estudiado un material de registro liolográfico para almacenamiento de la información óptica... more Se ha estudiado un material de registro liolográfico para almacenamiento de la información óptica compuesto por Azul de Metileno, Acrilamida, N,N'-metilenbisacrilamida, Trietanolamina y Alcohol Polivinílico como soporte. Se ha optimizado la composición siendo el rendimiento en difracción del 80% y sensibilidad entorno a 300 mj/cm^ para redes de difracción con frecuencias espaciales de 1000 líneas/mm. Palabras claves: rendimiento en difracción, sensibilidad energética, fotopolimerización, fotorreducción. Optimization of a holographic recording material for optical information storage The Holographic material for optical recording information composed by Methylene blue, Acrylamide, N,N'-methylenbisacryilamide, Triethanolamine and Polyvinylalcohol as binder is studied. Optimum composition is obtained with a diffraction efficiency of-80% achieved with an energetic sensitivity between 300 mj/cm^, and the spatial resolution is up to 1000 lines/mm.
Optics Express, 2021
Helicity and directionality control of scattered light by nanoparticles is an important task in d... more Helicity and directionality control of scattered light by nanoparticles is an important task in different photonic fields. In this paper, we theoretically demonstrate that scattered light of lossy spherical nanoparticles excited by using two counter-propagating dephased plane waves with opposite helicity ±1 and the adequate selection of dephase and intensity shows a well defined helicity and a controllable scattering directivity. Numerical examples of Si nanospheres are studied showing their potential application to directional nanoantennas with a well defined helicity. The proposed method is valid for any type of nanoparticle, not only lossy ones.
16th Congress of the International Commission for Optics: Optics as a Key to High Technology, Jul 23, 1993
Holographic Optics III: Principles and Applications, 1991
During the last few years, the number of intraocular lenses that have been implanted has grown co... more During the last few years, the number of intraocular lenses that have been implanted has grown considerably, thereby creating the need for an exhaustive study of the characteristics of such lenses as image-forming systems. In this paper, the spheric aberration of flat-convex intraocular lenses as measured by a holographic interferometer is discusses, and the results are compared with the technical data on the aberration that such a lens presents. The match between theory and experimentation is good.
Proceedings of SPIE - The International Society for Optical Engineering, 1997
ABSTRACT Multicolor display holography has been described by using some different techniques. Tho... more ABSTRACT Multicolor display holography has been described by using some different techniques. Those that allow white-light viewing of the final hologram generally involve several stages, some requiring accurate registration. The recording technique, the recording material and the processing are all important parts of the final color hologram. Various special techniques allow the production of holograms exhibiting different colors. Color control for reflection holograms usually implies the preswelling of the emulsion before the recording. In this paper we will describe different methods of obtaining different colors for reflection holography on silver halide photographic emulsion by means of chemical methods, other than the preswelling. By using a He-Ne laser at 632.8 nm for the recording, we can achieve a range of reconstruction wavelength from 550 nm to 700 nm by using different developments and bleachings as well as different temperatures during the processing. By measuring the coordinates of each point recorded, we will find its right wavelength. Thus, comparing them to those of the CIE diagram, we will know the exact location of each color in the horseshoe shape. This will allow us to choose the desired color and repeat it in the conditions previously experimented.
Holographic Materials IV, 1998
Holographic Materials IV, 1998
SPIE Proceedings, 2002
Ion this work we present a distortion of the usual HD curve due to the action of a high contrast ... more Ion this work we present a distortion of the usual HD curve due to the action of a high contrast developer, Kodak D8 on ultra fine grain emulsion. This effect has been found for emulsions BB640, with a mean grain size of 20 nm. This anomalous curve shows two ...
Practical Holography XVII and Holographic Materials IX, 2003
ABSTRACT In this work we have studied the characteristics of reflection gratings recorded with BB... more ABSTRACT In this work we have studied the characteristics of reflection gratings recorded with BB640 emulsions from Colourholographics Ltd. processed with a set of different developers and bleaching techniques. Overall diffraction efficiencies evaluated with spectral response curves result in values higher than 70% (80% taking into account reflection losses) for conventional fixation free rehalogenating bleaching processes, with very low scattering. A slightly lower value was obtained with reversal bleaching techniques, but with lower scattering in the recordings. For the latter, an analytical analysis of the spectral responses based on the Kogelnik's theory has been performed, leading to anomalous results regarding physical thickness of the hologram and the reply wavelength, a performance that points towards holographic profile distortions. We have also used a completely different processing scheme based on Kodak D8, a developer never used in reflection holography, with a direct bleach rendering 40% diffraction efficiency, a broad bandwidth and a reconstruction wavelength longer than the recording one.
Holographic Materials V, 1999
ABSTRACT The spectral sensitivity and the enhancement of the energetic sensitivity are important ... more ABSTRACT The spectral sensitivity and the enhancement of the energetic sensitivity are important points to the optimization of photopolymerizable materials. We have studied a polymeric system based on polyvinylalcohol as binder, monomers as acrylamide and dihydroxyethylenbisacrylamide and a photoinitiator system composed by triethanolamine and methylene blue. This system was irradiated with an Ar+ laser tuned at 514 nm, where this material do not abosrb. Obtaining diffraction efficiencies of 55 % with an energetic expositions of 500 mJcm(-2) A possible mechanism of initiation of the photopolymerization process has been proposed by the presence of semireduced methylene blue that has an absorption band at 520 nm.
SPIE Proceedings, 1999
The response curve D-Log E is the most important method to characterize photographic emulsions. I... more The response curve D-Log E is the most important method to characterize photographic emulsions. In this work we present the experimental study using a real time technique that can be applied to the improvement of the holographic properties of emulsions. We have exposured an Agfa Gevaert 8E56HD emulsion with an Argon laser tuned at 514 nm. After it, we measured
SPIE Proceedings, 2001
Two wave-mixing (TWM) is reported for an acrylamide based photopolymer at a wavelength of 633 nm ... more Two wave-mixing (TWM) is reported for an acrylamide based photopolymer at a wavelength of 633 nm where the material absorbs light. Measurements of diffraction efficiency where also made at 441. In TWM experiment, transfer of energy from the reference beam to the object beam is showed and the mechanism of the image formation is studied using real time measurements.
Holographic and Diffractive Techniques, 1996
Optics Communications, 1995
Nonlinear holographic characteristics of Agfa SE75HD plates processed with two developers were me... more Nonlinear holographic characteristics of Agfa SE75HD plates processed with two developers were measured. To assess the effects of nonlinear recording, reconstructed holographic images of a microline test object were numerically calculated by using these characteristics. The possibility of optimizing the recording parameters was demonstrated.
Journal of the Optical Society of America B, 2007
We develop a general procedure that allows the determination of the spectral transmittance and re... more We develop a general procedure that allows the determination of the spectral transmittance and reflectance at normal incidence for arbitrary one-dimensional continuous materials as well as the analysis of the timedomain propagation of pulses through them. This procedure consists of a generalization of Fresnel equations, and it is supported by an iterative algorithm also developed here: the polynomial fixed-point algorithm (PFPA). We apply these theoretical results to some concrete examples, such as determining the transmittance and reflectance for an absorptionless photonic crystal, an optical rugate filter, and a photonic crystal with periodic absorption. We also analyze the time-domain propagation of ultrashort Gaussian pulses through different structures.
Optical Engineering, 1995
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Papers by Luis Carretero Lopez