Examinando por Materia "Fast Fourier transforms"
Mostrando 1 - 4 de 4
Resultados por página
Opciones de ordenación
Ítem Digital opties tool for multi-purpose experimental applications(2010-01-01) Sierra-Sosa, D.-E.; Angel-Toro, L.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThis work presents the results concerning the application of a Discrete Fresnel Transform algorithm (DFT), which was upgraded for modeling and experimenting with scalar diffraction fields, whose characteristics are analyzed. The MATLAB® software environment was used to implement this algorithm, which allows the user to set the initial conditions, corresponding to the optical information at the input plane, by using a graphic friendly user interface (GUI). Then, by using the DFT algorithm, light propagation from the input to the output plane is achieved. The outputs of the algorithm are the maps corresponding to the 2-D distributions amplitude and phase-modulo 2p, or equivalently, the corresponding real and imaginary parts of the complex analytical field. Also, to assist the analysis, line profiles for these maps are provided. Results allow the user synthesizing Fresnel diffraction in presence of multiple components, like lenses, prisms, diffractive gratings, and holographic elements. Indeed, by implementing a series of successive steps, applications like image forming and spatial filtering can be demonstrated. The basis of the algorithm's architecture and some typical results, which closely resemble those from the experiments, are presented.Ítem Fast Spectral Formulations of Thin Plate Laser Heating with GPU Implementation(Institute of Electrical and Electronics Engineers Inc., 2020-01-01) Mejia-Parra D.; Arbelaiz A.; Moreno A.; Posada J.; Ruiz-Salguero O.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEIn the context of numerical methods, the problem of frequency-domain (spectral) simulations is crucial for the solution of Partial Differential Equations. Fast Fourier Transform (FFT) algorithms significantly reduce the computational cost of such simulations and enable parallelization using Graphics Processing Units (GPUs). In the particular subdomain of laser heating/cutting of rectangular metal plates, fast simulation is required for tool path planning, parameter optimization and additive manufacturing. The currently used methods include frequency-domain analytic solutions for single-beam and multi-beam laser heating. However, the problem of formulating these spectral problems in terms of Fourier methods and implementing them in efficient manner remains. To overcome these limitations, this article presents two different schemes that translate the problem of laser beam heating of metal plates into equivalent FFT problems. The results show significant improvements in terms of executions times, being 100× faster than current state-of-the-art algorithms. Future work needed involves the inclusion of stress analysis, complex plate geometries and non-constant material properties for the plate. © 2020 IEEE.Ítem Soap film analysis by speckle interferometer(SPIE-INT SOC OPTICAL ENGINEERING, 2003-01-01) Tebaldi, M.; Ángel, L.; Trivi, M.; Bolognini, N.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn this paper a soap film is characterized by using a speckle interferometer. The arrangement consists of a double-exposure specklegram obtained through a double-aperture system, by introducing a wedge in front of one aperture in one exposure. It is assumed that a uniform displacement of the diffuser is produced between exposures. The average intensity distribution and the changes experimented by the interferometric fringe visibility in the Fourier plane due to the introduction of a soap film in each exposure are analyzed.Ítem Speckle interferometric technique to assess soap films(ELSEVIER SCIENCE BV, 2004-01-02) Tebaldi, M; Angel, L; Bolognini, N; Trivi, M; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaAn speckle interferometric technique to monitor the thinning process of vertical soap film before the film rupture is presented. The interferometric arrangement consists in a double aperture pupil optical system which images an input diffuser. In a first step, a reference specklegram is stored in the computer buffer memory. Afterwards, the soap film is located in front of one pupil aperture, an uniform displacement of the diffuser is produced and a new speckle pattern is stored. The soap film status is characterized in terms of the changes that this dynamic phase object introduces in the correlation fringes obtained by applying a FFT algorithm to the resulting summed specklegram. This procedure is done in real time as far as the soap film evolves in the successive status. It is experimentally demonstrated that the soap film during drawing acts as a variable wedge. The correlation fringes behavior becomes an important tool to establish the wedge shaped soap film angle and the thickness variations. © 2003 Elsevier B.V. All rights reserved.