Alumbrar el pasado

Reseña del libro "El pionero de la luz: Alhacén y su Libro de la Óptica", por MARÍA LUISA CALVO PADILLA y publicado por Ediciones Complutense, Madrid, 2019Peer ReviewedPostprint (published version

Liquid crystal spatial light modulator with optimized phase modulation ranges to display multiorder diffractive elements

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First-order and multi-order diffractive lens using a device with 8P phase modulation range

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Roadmap on optical security

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The challenge of replacing the crystalline lens

La catarata o pérdida de transparencia del cristalino es un trastorno de la visión muy invalidante que ha sufrido la humanidad a lo largo de la historia. En las últimas décadas se trata con éxito mediante la sustitución de la lente natural por una lente artificial intraocular. Este estudio se centra en los aspectos ópticos, desde el diseño del implante a los efectos en el sistema visual, y en dos temas relacionados con la formación de imágenes de gran interés actualmente: a) los diseños de lentes intraoculares que, además de eliminar la catarata, corrigen parcialmente la presbicia, y b) la calidad de una lente intraocular evaluada por dos vías metodológicas distintas: una óptica (in vitro), en el laboratorio, y otra visual (in vivo) mediante el examen clínico de pacientes con implante. Las métricas que correlacionan ambos métodos buscan una predictibilidad más ajustada de los resultados posoperatorios. Ante la gran variedad de lentes intraoculares existente en la actualidad, con propiedades ópticas notablemente diferentes, se hace necesaria una selección personalizada del implante que mejor se adapte a las características del paciente y tenga en cuenta su estilo de vida.A la Agencia Estatal de Investigación del gobierno de España por la financiación del proyecto (PID2020-114582RB-I00 / AEI / 10.13039/501100011033).Peer ReviewedPostprint (published version

Extended depth of focus intraocular lens: Chromatic performance

We describe a first-and-second-diffractive-order intraocular lens ((1st,2nd)DIOL) within the class of hybrid refractive-diffractive designs for intraocular lenses (IOLs) and analyse its properties of focus extension and compensation of longitudinal chromatic aberration (LCA), particularly for lenses with low addition. Power, energy efficiency and their wavelength dependence are extended from monofocal IOL and conventional bifocal zeroth-and-first-diffractive-order IOL ((0th,1st)DIOL) to (1st,2nd)DIOL of low addition. Compensation of LCA is experimentally assessed in optical bench through the through-focus energy efficiency of three Tecnis IOLs with red, green and blue illuminations: ZA9003 (monofocal), ZKB00 (bifocal (0th,1st)DIOL with + 2.75 D add) and Symfony ZXR00. We prove Tecnis Symfony ZXR00 IOL can be considered an example of (1st,2nd)DIOL design of low addition, with LCA compensation in both the distance and intermediate foci, whereas the bifocal (0th,1st)DIOL does not compensate in the distance focus. However, the energy efficiency of (1st,2nd)DIOL for wavelengths other than the design wavelength is markedly more asymmetric.Postprint (published version

Image encryption system based on a nonlinear joint transform correlator for the simultaneous authentication of two users

We propose a new encryption system based on a nonlinear joint transform correlator (JTC) using the information of two biometrics (one digital fingerprint for each user) as security keys of the encryption system. In order to perform the decryption and authentication in a proper way, it is necessary to have the two digital fingerprints from the respective users whose simultaneous authentication is pursued. The proposed security system is developed in the Fourier domain. The nonlinearity of the JTC along with the five security keys given by the three random phase masks and the two digital fingerprints of the two users allow an increase of the system security against brute force and plaintext attacks. The feasibility and validity of this proposal is demonstrated using digital fingerprints as biometrics in numerical experiments.Peer ReviewedPostprint (published version

Image quality and security through nonlinear joint transform encryption

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Effects of using an encrypted image corrupted by noise and occlusion in a security system based on joint transform correlator and Gyrator transform

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SEDOPTICA newsletter: noticias de SEDOPTICA

El boletín de noticias de SEDOPTICA recoge la actividad de la sociedad y sus miembros en el tercer trimestre del año 2019.Peer ReviewedPostprint (published version