Analytic design of multiple-axis, multifocal diffractive lenses

In this Letter, we introduce an analytic procedure for designing diffractive lenses using the combination of wavefronts aberrated by Zernike polynomials. We show how to design amplitude-only, phase-only, continuous, and binary lenses providing equivalent results. As an example we apply it to the design of a multiple-axis, multifocal lens. The number of foci and their positions can be easily controlled. Theoretical predictions have been experimentally confirmed. The main advantage of this procedure is that, because it is simple and intuitive, it can be used successfully for the design of complex lenses

Wavefront sensing using diffractive elements

In this Letter, we introduce a wavefront slope sensor based on a diffractive element. The diffractive element wavefront sensor (DEWS) produces four double overlapping copies of the incoming wavefront acting like a combination of shearing and pyramidal sensors. The DEWS allows a simple and fast slope estimate. The wavefront sampling can be as high as the number of pixel assigned to cover a wavefront copy, and it can be modified with only binning the CCD pixels. The theory for designing the sensor, its application to extract local slope information, and a simple noise analysis are presented. An application example for atmosphere aberrated wavefronts is demonstrated

Elemento difractivo multifocal y método de fabricación

Elemento difractivo multifocal y método de fabricación, esta invención concierne al diseño de dispositivos ópticos multifocales, como son lentes y espejos multifocales, y específicamente a lentes de contacto y lentes intraoculares multifocales. El elemento difractivo multifocal propuesto se caracteriza por la utilización de un perfil de fase descrito por una función coseno cuyo argumento determina la distancia entre focos. El reparto de energía entre focos depende de la amplitud del perfil.Solicitud: 200201088 (13.05.2002)Nº Pub. de Solicitud: ES2208077A1 (01.06.2004)Nº de Patente: ES2208077B2 (16.05.2005

Lucky imaging speckle statistics applied to halo suppression

In ground based astronomy, the Lucky Imaging (LI) technique consists of selecting the best quality pictures among those that have been taken with a short exposure time to freeze the atmosphere distortions. Although it has different advantages, the peak intensity of a star is always surrounded by speckled light which, once averaged, provides the halo. The halo can make it difficult to detect faint companions immersed in it. In this paper, we take advantage of the speckle statistics to remove the halo and so to make more effective current detection techniques. Theoretical predictions are confirmed using experimental LI data. Finally, a photometry algorithm is also proposed.Funding by Ministerio de Economía y Competitividad, project AYA2016-78773-C2-1-P

Dispositivo óptico de focal variable

Dispositivo óptico de focal variable que comprende una pluralidad de filtros que tienen una distribución de fase determinada y soporte para filtros configurado para producir un desplazamiento de foco óptico cuando uno de los filtros es rotado con respecto a otro.Solicitud: 200900578 (25.02.2009)Nº Pub. de Solicitud: ES2323564A1 (20.07.2009)Nº de Patente: ES2323564B2 (05.05.2010

Digital coronagraphy: application to space telescope images

Optical coronagraphy is a high contrast image technique used in astronomy to reduce light around a host star and make viable the detection of faint companions and the exploration of circumstellar disks. Digital coronagraphy consists of the digital processing of non-coronagraphic images acquired by space telescopes in order to reproduce the operation of a standard optical coronagraph. Digital coronagraphy presents significant advantages as no real coronagraph or extra device has to be manufactured and sent to space. In this paper, comparison of digital and optical coronagraph performances is accomplished both by numerical simulations that include detection noise and the use of archived images from the Hubble Space Telescope. Our analysis indicates that the attainable contrast with both techniques is comparable, though the required Lyot stop in digital coronagraphy differs from the standard one. Furthermore, the evolution of contrast as a function of the distance to the main star that we have encountered with the optical coronagraph is similar to that shown by different authors for the optical NIC2/COR coronagraph. Finally, although digital coronagraphy cannot substitute optical coronagraphs, it can be considered as an interesting tool for the analysis of actual system performance.Ministerio de Economía, Industria y Competitividad, Gobierno de España (AYA2016-78773-C2-1-P).This research has made use of data reprocessed as part of the ALICE program, which was supported by NASA through grants HST-AR-12652 (PI: R. Soummer), HST-GO-11136 (PI: D. Golimowski), HST-GO-13855 (PI: E. Choquet), HST-GO-13331 (PI: L. Pueyo), and STScI Director’s Discretionary Research funds, and was conducted at STScI which is operated by AURA under NASA contrast NAS5-26555

Dispositivo óptico de aumento para cámara oscura

Solicitud: 202231511 (16.09.2022)Nº Pub. de Solicitud: ES1295930U (22.12.2022)Nº de Modelo de Utilidad: ES1295930Y (15.03.2023

Variables del estudiante, del profesor y del contexto en la predicción del rendimiento académico en Biología: Análisis desde una perspectiva multinivel

En el presente estudio se analiza la contribución de variables del alumno y variables del contexto en la predicción del rendimiento académico en Bachillerato. Se han obtenido información de 988 estudiantes, de último curso de Bachillerato y de sus 57 profesores de Biología. Los datos fueron analizados desde una perspectiva multinivel. Los resultados indican que, de la variabilidad observada en el rendimiento en Biología, el 85.6% se debe a las variables de nivel de estudiante mientras que el 14.4% restante corresponde a las variables de nivel de clase. A nivel de estudiante. el rendimiento en Biología se encontró asociado con el enfoque de aprendizaje, con los conocimientos previos, con el absentismo escolar y con el nivel educativo de los padres. A nivel de clase, el rendimiento únicamente estuvo asociado con el enfoque de enseñanza del profesor. y no directamente, sino a través del enfoque de estudio del alumno

Planetary system detection by estimating the covariance of coronagraphic lucky images

In this paper, we review two different methods to increase image contrast and propose the combination of both to detect faint companions surrounding a host star. Coronagraphy allows us to block light coming from the host star so that the residual star light can be reduced by several orders of magnitude. On the other hand, estimating the Covariance of Lucky Images (COELI) is a proven method to detect faint companions from ground-based telescope images. The dynamic range of the detection camera limits this technique. Hence, the application of COELI to coronagraphic images may increase the magnitude range of the detectable companions. COELI only requires the existence of a reference, which can be obtained using an existing stellar companion or using a coronagraphic mask designed to create a faint image of the host star.We provide an analysis of the combination of the techniques by processing coronagraphic images obtained by the William Herschel Telescope.We acknowledge funding from Ministerio de Economía y Competitividad, project AYA2016-78773-C2-1-P

Quaternary adaptive optics

We present a new Point Diffraction Interferometer (PDI). Binary adaptive optics (BAO) and Quaternary Adaptive Optics (QAO) can be performed with the help of this PDI as a wavefront sensor. The PDI interferogram, once binarized, is used in two consecutive steps to produce a quaternary mask with phase values 0, π/2, π and 3π/2. The addition of the quaternary mask compensates for the aberrated wavefront and allows us to reach a Strehl ratio of about 0.81. We have verified through computer simulations that the use of QAO depends on the number of actuators of the compensating device to achieve effective compensation. The technique was successfully validated through an experiment.Ministerio de Economía y Competitividad (MINECO) (AYA2016-78773-C2-1-P)