Person:
Belenguer Dávila, Tomás

First Name

Tomás

Last Name

Belenguer Dávila

URI

https://hdl.handle.net/20.500.14352/79990

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Óptica y Optometría

Department

Óptica

Area

Optica

Identifiers

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Now showing 1 - 10 of 26

SAFARI optical system architecture and design concept
(Proceedings of SPIE, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 2016) Pastor Sempere, Carmen; Jellema, Willem; Zuluaga Ramírez, Pablo; Arrazola, David; Fernández Rodríguez, M.; Belenguer Dávila, Tomás; González Fernández, Luis M.; Audley, Michael D.; Evers, Jaap; Eggens, Martin; Torres Redondo, Josefina; Najarro, Francisco; Roelfsema, Peter
SpicA FAR infrared Instrument, SAFARI, is one of the instruments planned for the SPICA mission. The SPICA mission is the next great leap forward in space-based far-infrared astronomy and will study the evolution of galaxies, stars and planetary systems. SPICA will utilize a deeply cooled 2.5m-class telescope, provided by European industry, to realize zodiacal background limited performance, and high spatial resolution. The instrument SAFARI is a cryogenic grating-based point source spectrometer working in the wavelength domain 34 to 230 μm, providing spectral resolving power from 300 to at least 2000. The instrument shall provide low and high resolution spectroscopy in four spectral bands. Low Resolution mode is the native instrument mode, while the high Resolution mode is achieved by means of a Martin-Pupplet interferometer. The optical system is all-reflective and consists of three main modules; an input optics module, followed by the Band and Mode Distributing Optics and the grating Modules. The instrument utilizes Nyquist sampled filled linear arrays of very sensitive TES detectors. The work presented in this paper describes the optical design architecture and design concept compatible with the current instrument performance and volume design drivers.
Optical inspection of liquid crystal variable retarder inhomogeneities
(Applied Optics, 2010) Quiroga Mellado, Juan Antonio; Uribe Patarroyo, Néstor R.; Vargas Balbuena, Javier; Álvarez Herrero, Alberto; Belenguer Dávila, Tomás
Liquid crystal variable retarders (LCVRs) are starting to be widely used in optical systems because of their capacity to provide a controlled variable optical retardance between two orthogonal components of incident polarized light or to introduce a known phase shifting (PS) between coherent waves, both by means of an applied voltage. Typically, the retardance or PS introduced by an LCVR is not homogeneous across the aperture. On the one hand, the LCVR glass substrates present a global bend that causes an overall variation of the retardance or PS. On the other hand, in the manufacturing process of an LCVR, there sometimes appears a set of micro-air bubbles that causes local retardance or PS inhomogeneities. In this work, we present an interferometric technique based on a Mach-Zehnder interferometer that is insensitive to vibrations and capable of inspecting and characterizing the LCVR's retardance or PS inhomogeneities. The feasibility of the proposed method is demonstrated in the experimental results, where the LCVR retardance is measured with an error of about 0:2 rad. The thickness of possible micro-air bubbles is obtained with a resolution of about 50 nm.
Analysis of the principal component algorithm in phase-shifting interferometry
(Optics Letters, 2011) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Belenguer Dávila, Tomás
We recently presented a new asynchronous demodulation method for phase-sampling interferometry. The method is based in the principal component analysis (PCA) technique. In the former work, the PCA method was derived heuristically. In this work, we present an in-depth analysis of the PCA demodulation method.
Substrate mode hologram for optical interconnects
(Optics Communications, 1998) Cheben, Pavel; Calvo Padilla, María Luisa; Belenguer Dávila, Tomás; Núñez Peral, Armonía
A novel method of substrate mode hologram (SMH) design and fabrication is presented. The coupling between a homogeneous plane wave and an arbitrary free propagating wave is achieved via a total internally reflected (TIR) wave. The input slanted plane grating, recorded in an orthochromatic holographic medium, accomplishes the homogeneous plane wave to TIR wave coupling. The TIR wave is transformed to the free propagating wave by the output aperiodic aplanar inhomogeneous grating recorded in a panchromatic holographic medium. Aberration-free conversion between the incident plane wave and the Gaussian wave is reported for coupling efficiency of 57%.
Multi-plane phase retrieval methods to recover free-aberrations object complex field via SLM
(Óptica Pura y Aplicada, 2017) Restrepo Gómez, René; Belenguer Dávila, Tomás
This paper explains two iterative phase recovery methods where the goal of each one is different. The Phase Diversity method is used to recover the wavefront aberrations in optical incoherent imaging systems when an extended object is illuminated. The purpose of the Multi-plane Phase Retrieval method is recovering the object complex field seen from the image plane, therefore the object has to be illuminated with coherent light. Both methods are simultaneously used to pick out the aberrations and free aberrations object phase. The use of both methods is proposed as a methodology for the integration of optical instruments.
Embedded Fiber Bragg Grating Sensors for Monitoring Temperature and Thermo-Elastic Deformations in a Carbon Fiber Optical Bench
(Sensors, 2023) Fernández Medina, Ana; Frövel, Malte; López Heredero, Raquel; Belenguer, Tomás; Belenguer Dávila, Tomás; de la Torre, Antonia; Moravec, Carolina; San Julián, Ricardo; Gonzalo, Alejandro; Cebollero, María; Álvarez-Herrero, Alberto
A composite optical bench made up of Carbon Fiber Reinforced Polymer (CFRP) skin and aluminum honeycomb has been developed for the Tunable Magnetograph instrument (TuMag) for the SUNRISE III mission within the NASA Long Duration Balloon Program. This optical bench has been designed to meet lightweight and low sensitivity to thermal gradient requirements, resulting in a low Coefficient of Thermal Expansion (CTE). In addition to the flight model, a breadboard model identical to the flight one has been manufactured, including embedded fiber Bragg temperature and strain sensors. The aim of this is to explore if the use of distributed fiber Bragg gratings (FBGs) can provide valuable information for strain and temperature mapping of an optical instrument on board a space mission during its operation as well as its on-ground testing. Furthermore, surface-mounted strain FBG sensors and thermocouples have been installed in the optical bench for intercomparison purposes. This paper presents the results obtained from a thermal vacuum test consisting of three thermal cycles with stabilization steps at 100 °C, 60 °C, 20 °C and −20 °C. Experimental results provide information about how FBG embedded temperature sensors can provide a proper and quick response to the temperature changes of the optical bench and that embedded FBG strain sensors are able to measure micro-deformation induced in a close-to-zero CTE optical bench.
Local fringe density determination by adaptive filtering
(Optics Letters, 2011) Vargas Balbuena, Javier; Quiroga Mellado, Juan Antonio; Belenguer Dávila, Tomás
We demonstrate a method to easily and quickly determine the local fringe density map of a fringe pattern. The method is based on an isotropic adaptive bandpass filter that is tuned at different frequencies. The modulation map after applying a specific bandpass frequencies filter presents a maximum response in the regions where the bandpass filter and fringe frequencies coincide. We show a set of simulations and experimental results that prove the effectiveness of the proposed method.
High dynamic range imaging method for interferometry
(Optics Communications, 2011) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Restrepo, R.; Belenguer Dávila, Tomás
We demonstrate a method to easily and quickly extend the dynamic range imaging capabilities of the camera in a typical interferometric approach. The camera dynamic range is usually low and limited to 256 gray levels. Also, it is well known that one may have over or under-exposed regions in the interferogram (due to non-uniform illumination) which makes these image regions not reliable. In our proposed method it is not necessary to obtain or use the non-linear camera response curve in order to extend the camera dynamic range. We obtain a sequence of differently exposed interferograms, typically five or six; after that, we compute the corresponding normalized fringe patterns and modulation maps using a typical normalization method. These normalized patterns are combined through a temporal weighted average using as weights the corresponding modulation maps. We show a set of experimental results that prove the effectiveness of the proposed method.
Direct demodulation of closed-fringe interferograms based on active contours
(Optics Letters, 2010) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Belenguer Dávila, Tomás
We demonstrate a method to directly demodulate closed-fringe interferograms using a kind of active contour called a snake. This method can be used to demodulate a single closed-fringe interferogram when its background illumination and/or contrast terms have a spatial frequency similar to the spatial frequency of the equivalent normalized interferogram. Among other cases, this problematic usually appears in interferometry when spurious reflection appears in the interferogram. In these situations, typical Fourier-based methods are of no help. We show a set of simulations and experimental results that prove the effectiveness of the proposed method.
Surface irregularity factor as a parameter to evaluate the fatigue damage state of CFRP
(Materials, 2015) Zuluaga Ramírez, Pablo; Frövel, Malte; Belenguer Dávila, Tomás; Salazar, Felix
This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL) and realistic variable amplitude loads (VAL), representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications.