Person: Sánchez Brea, Luis Miguel
Universidad Complutense de Madrid
Faculty / Institute
Now showing 1 - 3 of 3
PublicationOptimal phase distributions for polygonal Fresnel lenses(IEEE, 2010) Alda, Javier; Salgado Remacha, Francisco Javier; Sánchez Brea, Luis Miguel; Rico-García, José María; González, Francisco JavierPolygonal Fresnel zone plates can be configured in a variety of forms depending on the number of sides of the polygon and the number of phase steps used. This contribution deals with some specific polygonal designs that tessellate the plane: triangles, squares, and hexagons. The phase distribution is chosen as a continuous one to form a polygonal kinoform. The selected designs have been simulated and its behaviour compared. Although their performance is worse than the circular Fresnel plate, they may present some other advantages as the tessellation capability, and the possibility to fabricate them as extruded profiles. PublicationFourier series diffractive lens with extended depth of focus(Elsevier, 2023-04-11) Soria García, Ángela; Sánchez Brea, Luis Miguel; Hoyo Muñoz, Jesús, del; Torcal Milla, Francisco José; Gómez Pedrero, José AntonioAngular diffractive lenses have been proven to achieve a narrow beam waist with a long depth of focus. We generalize these type of lenses by defining the angular distribution of the focal length as a Fourier series. The Fourier coefficients of the lens are optimized, using Particle Swarm Optimization algorithm, to minimize the beam width and increase its uniformity for a given depth of focus. In order to obtain a fast simulation during the optimization process, we used Chirp Z-transform algorithm. Finally, we performed an experimental verification of the results using a Spatial Light Modulator. The Fourier series diffractive lens presents a more uniform and narrower beam than previous angular lenses, in both simulations and experiments. These results may find applications in the design of contact and intraocular lenses with extended depth of focus, laser focusing and imaging systems. PublicationOptimized square Fresnel zone plates for microoptics applications(SPIE, 2009-06-17) Rico-García, José María; Salgado Remacha, Francisco Javier; Sánchez Brea, Luis Miguel; Alda, JavierPolygonal Fresnel zone plates with a low number of sides have deserved attention in micro and nanoptics, because they can be straightforwardly integrated in photonic devices, and, at the same time, they represent a balance between the high-focusing performance of a circular zone plate and the easiness of fabrication at micro and nano-scales of polygons. Among them, the most representative family are Square Fresnel Zone Plates (SFZP). In this work, we propose two different customized designs of SFZP for optical wavelengths. Both designs are based on the optimization of a SFZP to perform as close as possible as a usual Fresnel Zone Plate. In the first case, the criterion followed to compute it is the minimization of the difference between the area covered by the angular sector of the zone of the corresponding circular plate and the one covered by the polygon traced on the former. Such a requirement leads to a customized polygon-like Fresnel zone. The simplest one is a square zone with a pattern of phases repeating each five zones. On the other hand, an alternative SFZP can be designed guided by the same criterion but with a new restriction. In this case, the distance between the borders of different zones remains unaltered. A comparison between the two lenses is carried out. The irradiance at focus is computed for both and suitable merit figures are defined to account for the difference between them.