Person: Bernabéu Martínez, Eusebio
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First Name
Eusebio
Last Name
Bernabéu Martínez
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Area
Optica
Identifiers
5 results
Search Results
Now showing 1 - 5 of 5
Item A generalization of Prentice's law for lenses with arbitrary refracting surfaces(Ophthalmic & Physiological Optics (OPO), 1998) Canabal Boutureira, Héctor Alfonso; Gómez Pedrero, José Antonio; Alonso Fernández, José; Bernabéu Martínez, EusebioA generalization of the Prentice's law is presented in this paper. The idea consists of removing some (but not all) of the approximations that comprise the paraxial approach. In that way, we obtain a new formulation that permits us to compute the prismatic power of a lens made up of arbitrary refracting surfaces, and to improve the precision obtained by Prentice's law when applied to monofocal lenses. The resulting formalism is simple and manageable and its derivation leads us to a precise definition of the local dioptric power matrix, introduced in a previous paper, as well as a better understanding of the same.Item Laser beam deflectometry based on a subpixel resolution algorithm(Optical Engineering, 2001) Canabal Boutureira, Héctor Alfonso; Alonso Fernández, José; Bernabéu Martínez, EusebioA deflectometric method for the characterization of optical systems is presented. It is based on the use of a CCD camera and a subpixel resolution algorithm for the measurement of the deflection of a laser beam that propagates through the system. To obtain accurate results, three different algorithms for measuring the position of the deflected beam are tested and compared. Based on this comparison, an algorithm based on the calculation of the phase of the fast Fourier transform (FFT) is selected, and an accuracy of 0.024 pixels is obtained on the determination of the beam position in our setup. Using an XY scanning stage, the proposed method is completely automated and applied for the characterization of ophthalmic lenses. In this application, the gradients of the wavefront refracted by the lens are measured directly, and from them, the thickness and the local power of the lens are computed.Item Deflectometric measurement of mechanical spectacle lens deformation(Ophtalmic and Physiological Optics, 2000) Peral Cerda, María Asunción; Alonso Fernández, José; Canos Sanz, Joán; Bernabéu Martínez, EusebioThe warpage of a set of six hard resin spherical lenses was measured when they were compressed by means of the tangential force exerted by a metal frame. The technique employed to measure the lenses improves over previous work both because greater precision is achieved, and because radii of curvature are measured in two perpendicular meridians. In this work, a representative sample of lenses has been used in order to test the way in which deformation depends on lens power and base. It is found that the induced warpage is enough to move the tested lenses between different base families, spoiling the initial design of the manufacturer.Item Optical autofocus for high resolution laser photoplotting(Photonic Materials, Devices, and Applications, 2005) Alonso Fernández, José; Crespo Vázquez, Daniel; Jiménez Castillo, Isidoro; Bernabéu Martínez, Eusebio; Badenes, Goncal; Abbott, Derek; Serpenguzel, AliAn all optical autofocus has been designed and tested for tight line width control in a high NA laser photoplotter system. The laser system is based in a GaN semiconductor laser with power 30 mW and wavelength 405 nm. The advantage of using this laser, despite the relatively long wavenlength, is compactness and easy for high frequency modulation. The autofocus system is based in a secondary 635 nm GaAlAs laser without need for wavelength, neither power stabilization. The two beams are delivered coaxially through the focusing lens by means of a dichroic beamsplitter. Focusing lens need no correction for chromatic aberration, as this is compensed by appropriate autofocus beam divergence. After reflection in the sample, the autofocus beam is separated from the returning writing beam and then guided to a collimation sensor, in which defocus of about 1/20 of the Rayleigh range of the writing beam can be detected and compensated by an analogue PID electronic control. Stable linewidth within 5% is achieved with different numerical aperture focusing lenses.Item Colorimetric matching by minimum-square-error fitting(Applied Optics, 1994) Quiroga Mellado, Juan Antonio; Alonso Fernández, José; Zoido Chamorro, Jesús Manuel; Bernabéu Martínez, EusebioLeast-squares approximation can be used in image-based colorimetry once the set of sampling functions is selected. We discuss the accuracy obtained in earlier research, and we compare it with a better calculation method.