Articles

Articles 28 records found  previous9 - 18next  jump to record: Search took 0.00 seconds. 
9.
31 p, 2.3 MB Optical image encryption technique based on deterministic phase masks / Zamrani, Wiam (Institut National des Postes et Telecommunications (Marroc)) ; Ahouzi, Esmail (Institut National des Postes et Telecommunications (Marroc)) ; Lizana Tutusaus, Ángel (Universitat Autònoma de Barcelona. Departament de Física) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física) ; Yzuel Giménez, María Josefa (Universitat Autònoma de Barcelona. Departament de Física)
The double-random phase encoding (DRPE) scheme, which is based on a 4f optical correlator system, is considered as a reference for the optical encryption field. We propose a modification of the classical DRPE scheme based on the use of a class of structured phase masks, the deterministic phase masks. [...]
2016 - 10.1117/1.OE.55.10.103108
Optical engineering, Vol. 55, Num. 10 (Oct 2016) , p. 103108  
10.
41 p, 3.4 MB Polarization gating based on Mueller matrices / Lizana Tutusaus, Ángel (Universitat Autònoma de Barcelona. Departament de Física. Grup d'Òptica) ; Van Eeckhout, Albert (Universitat Autònoma de Barcelona. Departament de Física. Grup d'Òptica) ; Adamczyk, Kamil (Universitat Autònoma de Barcelona. Departament de Física. Grup d'Òptica) ; Rodríguez, Carla (Universitat Autònoma de Barcelona. Departament de Física. Grup d'Òptica) ; Escalera Merino, Juan Carlos (Universitat Autònoma de Barcelona. Departament de Física. Grup d'Òptica) ; Garcia-Caurel, Enric (Université Paris Saclay. Laboratoire de Physique des Interfaces et des Couches Minces) ; Moreno, Ignacio (Universidad Miguel Hernández. Departamento de Ciencia de Materiales, Óptica y Tecnología Electrónica) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física. Grup d'Òptica)
We present mathematical formulas generalizing polarization gating (PG) techniques. PG refers to a collection of imaging methods based on the combination of different controlled polarization channels. [...]
2017 - 10.1117/1.JBO.22.5.056004
Journal of biomedical optics, Vol. 22, issue 5 (May 2017) , p. 56004-1-56004-14  
11.
4 p, 361.0 KB Conical refraction as a tool for polarization metrology / Peinado Capdevila, Alba (Universitat Autònoma de Barcelona. Departament de Física) ; Turpin Avilés, Alejandro (Universitat Autònoma de Barcelona. Departament de Física) ; Lizana Tutusaus, Ángel (Universitat Autònoma de Barcelona. Departament de Física) ; Fernández, Estefania (Universitat Autònoma de Barcelona. Departament de Física) ; Mompart Penina, Jordi (Universitat Autònoma de Barcelona. Departament de Física) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física)
A method for polarization metrology based on the conical refraction (CR) phenomenon, occurring in biaxial crystals, is reported. CR transforms an input Gaussian beam into a light ring whose intensity distribution is linked to the incoming polarization. [...]
2013 - 10.1364/OL.38.004100
Optics letters, Vol. 38, No. 20 (15 October 2013) , p. 4100-4103  
12.
3 p, 409.3 KB Enhancement of the broadband modulation diffraction efficiency of liquid-crystal displays / Albero, Jorge (Universidad Miguel Hernández. Departamento de Ciencia de Materiales, Optica y Tecnología Electrónica) ; Moreno Soriano, Ignacio (Universidad Miguel Hernández. Departamento de Ciencia de Materiales, Optica y Tecnología Electrónica) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física)
We report a method to maximize the broadband modulation diffraction efficiency of liquid-crystal spatial light modulators for polychromatic applications requiring a wide range of wavelengths. An optimized encoding pattern based on the minimum Euclidean projection principle is applied in order to increase the diffraction efficiency at large wavelengths that exhibit phase modulation depth lower than 2p. [...]
2012 - 10.1364/OL.37.000052
Optics letters, Vol. 37, No. 1 (1 January 2012) , p. 52-54  
13.
3 p, 286.8 KB Combined Mueller and Jones matrix method for the evaluation of the complex modulation in a liquid-crystal-on-silicon display / Moreno Soriano, Ignacio (Universidad Miguel Hernández. Departamento de Ciencia de Materiales, Optica y Tecnología Electrónica) ; Lizana Tutusaus, Ángel (Universitat Autònoma de Barcelona. Departament de Física) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física) ; Márquez Ruiz, Andrés (Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal) ; Iemmi, Claudio (Universidad de Buenos Aires. Departamento de Fisica) ; Yzuel Giménez, María Josefa (Universitat Autònoma de Barcelona. Departament de Física)
We apply the polar decomposition of the Mueller matrix describing a liquid-crystal-on-silicon display to identify the diattenuator, depolarizer, and retarder contributions as a function of the gray level. [...]
2008 - 10.1364/OL.33.000627
Optics letters, Vol. 33, No. 6 (15 March 2008) , p. 627-629  
14.
3 p, 74.1 KB Improved expressions for performance parameters for complex filters / Sheppard, Colin J. R. (National University of Singapore. Division of Bioengineering) ; Ledesma, Silvia (Universidad de Buenos Aires. Departamento de Física) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física) ; Escalera Merino, Juan Carlos (Universitat Autònoma de Barcelona. Departament de Física)
Improved expressions are given for the performance parameters for transverse and axial gains for complex pupil filters. These expressions can be used to predict the behavior of filters that give a small axial shift in the focal intensity maximum and also predict the changes in gain for different observation planes.
2007 - 10.1364/OL.32.001713
Optics letters, Vol. 32, No. 12 (15 June 2007) , p. 1713-1715  
15.
3 p, 226.9 KB Tailoring the depth of focus for optical imaging systems using a Fourier transform approach / Davis, Jeffrey A. (San Diego State University. Department of Physics) ; Tuvey, C. Stewart (San Diego State University. Department of Physics) ; López Coronado, Octavio (Universitat Autònoma de Barcelona. Departament de Física) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física) ; Yzuel Giménez, María Josefa (Universitat Autònoma de Barcelona. Departament de Física)
We show how to tailor the depth of focus for an optical system using pupil functions obtained from a Fourier transform approach. These complex amplitude and phase pupil functions are encoded onto a single liquid-crystal spatial light modulator. [...]
2007 - 10.1364/OL.32.000844
Optics letters, Vol. 32, No. 7 (1 April 2007) , p. 844-846  
16.
3 p, 508.0 KB Achromatic diffractive lens written onto a liquid crystal display / Márquez Ruiz, Andrés (Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal) ; Iemmi, Claudio (Universidad de Buenos Aires. Departamento de Fisica) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física) ; Yzuel Giménez, María Josefa (Universitat Autònoma de Barcelona. Departament de Física)
We propose a programmable diffractive lens written onto a liquid crystal display (LCD) that is able to provide equal focal lengths for several wavelengths simultaneously. To achieve this goal it is necessary that the LCD operate in the phase-only regime simultaneously for the different wavelengths. [...]
2006 - 10.1364/OL.31.000392
Optics letters, Vol. 31, No. 3 (1 February 2006) , p. 392-394  
17.
3 p, 93.3 KB Integration in the Fourier domain for restoration of a function from its slope : comparison of four methods / Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física) ; Yaroslavsky, Leonid P. (Tel Aviv University. Department of Interdisciplinary Studies) ; Moreno Soriano, Alfonso (Universitat Autònoma de Barcelona. Departament de Física) ; Yzuel Giménez, María Josefa (Universitat Autònoma de Barcelona. Departament de Física)
In some measurement techniques the profile, f(x), of a function should be obtained from the data on measured slope f'(x) by integration. The slope is measured in a given set of points, and from these data we should obtain the profile with the highest possible accuracy. [...]
2002 - 10.1364/OL.27.001986
Optics letters, Vol. 27, No. 22 (15 November 2002) , p. 1986-1988  
18.
3 p, 290.0 KB Evaluation and correction of aberrations in an optical correlator by phase-shifting interferometry / Iemmi, Claudio (Universidad de Buenos Aires. Departamento de Fisica) ; Moreno Soriano, Alfonso (Universitat Autònoma de Barcelona. Departament de Física) ; Nicolás Román, José (Universitat Autònoma de Barcelona. Departament de Física) ; Campos Coloma, Juan (Universitat Autònoma de Barcelona. Departament de Física)
We propose a new method for evaluating and correcting aberrations in a Vander Lugt correlator. The technique is achieved with liquid-crystal displays of the correlator and allows the task to be performed in situ. [...]
2003 - 10.1364/OL.28.001117
Optics letters, Vol. 28, No. 13 (1 July 2003) , p. 1117-1119  

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