Person: Sánchez Brea, Luis Miguel
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First Name
Luis Miguel
Last Name
Sánchez Brea
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Óptica
Area
Optica
Identifiers
6 results
Search Results
Now showing 1 - 6 of 6
Item Optimal phase distributions for polygonal Fresnel lenses(Proceedings of the Fourth European Conference on Antennas and Propagation, 2010) Alda Serrano, 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.Item Binary gratings with random heights(Applied Optics, 2009) Rico García, José María; Sánchez Brea, Luis MiguelWe analyze the far-field intensity distribution of binary phase gratings whose strips present certain randomness in their height. A statistical analysis based on the mutual coherence function is done in the plane just after the grating. Then, the mutual coherence function is propagated to the far field and the intensity distribution is obtained. Generally, the intensity of the diffraction orders decreases in comparison to that of the ideal perfect grating. Several important limit cases, such as low- and high-randomness perturbed gratings, are analyzed. In the high-randomness limit, the phase grating is equivalent to an amplitude grating plus a “halo.” Although these structures are not purely periodic, they behave approximately as a diffraction grating.Item Far field of binary phase gratings with errors in the height of the strips(Modeling Aspects in Optical Metrology II, 2009) Rico García, José María; Sánchez Brea, Luis MiguelDiffraction gratings are not always ideal but, due to the fabrication process, several errors can be produced. In this work we show that when the strips of a binary phase diffraction grating present certain randomness in their height, the intensity of the diffraction orders varies with respect to that obtained with a perfect grating. To show this, we perform an analysis of the mutual coherence function and then, the intensity distribution at the far field is obtained. In addition to the far field diffraction orders, a "halo" that surrounds the diffraction order is found, which is due to the randomness of the strips height.Item Diffractive optical elements with square concentric rings of equal width(Microwave and Optical Technology Letters, 2010) Alda Serrano, Javier; Sánchez Brea, Luis Miguel; Salgado Remacha, Francisco Javier; Rico García, José MaríaA diffractive optical element having equal-width concentric square rings is analyzed in this article. This constant width makes possible its realization using spatial light modulators or square pixels phase screens. It allows a simple analytical treatment, and the element is also simulated using the Rayleigh-Sommerfeld approach. An experimental verification of its performance has been compared with the simulated results.Item Diffractive performance of square Fresnel zone plates(Optics Communications, 2009) Alda Serrano, Javier; Rico García, José María; Salgado Remacha, Francisco Javier; Sánchez Brea, Luis MiguelWe analyze the optical behavior of square Fresnel zones plates. A theoretical analysis and numerical simulations based on the Rayleigh-Sommerfeld approach have been developed analyzing properties such as the depth of focus and the intensity of the focus in terms of the number of zones. In addition, an experimental verification has been performed using a Spatial Light Modulator to implement the designed square Fresnel zones plates.Item Optimized square Fresnel zone plates for microoptics applications(Modeling Aspects in Optical Metrology II., 2009) Rico García, José María; Salgado Remacha, Francisco Javier; Sánchez Brea, Luis Miguel; Alda Serrano, 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.