Searched for: faculty%3A%22Applied%255C%252BSciences%22
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Petrik, P. (author), Fodor, B. (author), Agocs, E. (author), Kozma, P. (author), Nador, J. (author), Kumar, N. (author), Endres, J. (author), Juhasz, G. (author), Major, C. (author), Pereira, S.F. (author), Lohner, T. (author), Urbach, H.P. (author), Bodermann, B. (author), Fried, M. (author)
conference paper 2015
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Cisotto, L. (author), Zhu, Y. (author), Pereira, S.F. (author), Urbach, H.P. (author)
Finding a fast and precise method to measure the side-wall angle of periodic (or non-periodic) structures is still a very challenging problem in lithographic applications. For this reason, over the years, many techniques have been proposed to circumvent this limitation, with the final goal to give the most precise geometrical description of...
conference paper 2015
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Pereira, S.P. (author), Vuik, K. (author), Pinho, F.T. (author), Nobrega, J.M. (author)
The present work explores the massively parallel capabilities of the most advanced architecture of graphics processing units (GPUs) code named “Fermi”, on a two-dimensional unstructured cell-centred finite volume code. We use the SIMPLE algorithm to solve the continuity and momentum equations that was fully ported to the GPU. The benefits of...
conference paper 2013
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Polo, A. (author), Pereira, S.F. (author), Urbach, H.P. (author)
We analytically demonstrate that Phase Retrieval (PR) from defocused intensity measurements is achievable using a single measurement plane. Following this approach, the predicted plane is found at a defocus distance of 4? optical unit. Experimental results confirm the theoretical predictions
conference paper 2013
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Pereira, S.F. (author), Wiegman, A. (author), Kumar, N. (author), Da Costa Assafrao, A. (author), Polo, A. (author), Wei, L. (author), Van Haver, S. (author)
Measurement techniques to determine the aberration of an optical system, by obtaining through-focus intensity images that are produced when the object is a point source at infinity, are shown. The analysis of the aberrations is made using the extended version of the Nijboer-Zernike diffraction theory. This theory provides a semi analytical...
conference paper 2012
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Van Haver, S. (author), Braat, J.J.M. (author), Pereira, S.F. (author)
We propose a measurement approach that allows the determination of aberrations of a microlens by analyzing the through-focus intensity image it produces when the object is a point source. To simulate image formation by a microlens we apply the extended version of the Nijboer-Zernike diffraction theory (ENZ) that uses the Debye diffraction...
conference paper 2010
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Meisner, J.A. (author), Jaffe, W.J. (author), Le Poole, R.S. (author), Pereira, S.F. (author), Quirrenbach, A. (author), Raban, D. (author), Vosteen, A. (author)
The Polarization-Based Collimated Beam Combiner efficiently produces pairwise interference between beams from multiple telescopes. An important feature is achieving ”Photometric Symmetry” whereby interference measurements have no first-order sensitivity to wavefront perturbations (or photometric variations following spatial filtering) which...
conference paper 2010
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Pereira, S.F. (author), Spronck, J.F.P. (author), Kutchoukov, V.G. (author), Bachor, H.A. (author)
We present simulations and experimental results on encoding information both in the longitudinal and transverse directions of an optical beam reflected from an asymmetric pit. The method does not require interferometric detection but is based on intensity measurements using a simple quadrant detector. In addition, we also discuss the...
conference paper 2010
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Pereira, S.F. (author), Spronck, J.F.P. (author), Kutchoukov, V.G. (author), Bachor, H.A. (author)
We present simulations and experimental results on encoding information both in the longitudinal and transverse directions of an optical beam reflected from an asymmetric pit. The method does not require interferometric detection but is based on intensity measurements using a simple quadrant detector. In addition, we also discuss the...
conference paper 2010
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Assafrao, A.C. (author), Pereira, S.F. (author), Urbach, H.P. (author), Fery, C. (author), Von Riewel, L. (author), Knappmann, S. (author)
A simplified computational model for super resolution effect in optical discs is proposed and simulations are compared with experimental results, providing basic understanding of this phenomenon. Simulations show that resolution beyond the diffraction limit is achieved and signal destruction occurs at some frequencies when the super resolution...
conference paper 2010
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Urbach, H.P. (author), Pereira, S.F. (author), Broer, D.J. (author)
We determine field distributions in the pupil of a high NA lens, that give, for a given power incident on the lens, the maximum electric field amplitude in focus in a specific direction. We consider in particular the cases of maximum longitudinal and maximum transverse components. The distribution of the maximum longitudinal component in the...
conference paper 2009
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Spronck, J.F.P. (author), Los, J.W.N. (author), Pereira, S.F. (author)
The optical properties of materials are wavelength-dependent. This property, called dispersion, affects the performance of a wide-band nulling interferometer by inducing wavelength-dependent phase differences between the arms of the interferometer. In this paper, we analyze the influence of dispersion in nulling interferometers for exoplanet...
conference paper 2008
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Van Haver, S. (author), Janssen, O.T.A. (author), Braat, J.J.M. (author), Janssen, A.J.E.M. (author), Urbach, H.P. (author), Pereira, S.F. (author)
In this paper we introduce a new mask imaging algorithm that is based on the source point integration method (or Abbe method). The method presented here distinguishes itself from existing methods by exploiting the through-focus imaging feature of the Extended Nijboer-Zernike (ENZ) theory of diffraction. An introduction to ENZ-theory and its...
conference paper 2008
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Janssen, O.T.A. (author), Van Haver, S. (author), Janssen, A.J.E.M. (author), Braat, J.J.M. (author), Urbach, H.P. (author), Pereira, S.F. (author)
Results are presented of mask imaging using the Extended Nijboer-Zernike (ENZ) theory of diffraction. We show that the efficiency of a mask imaging algorithm, derived from this theory, can be increased. By adjusting the basic Finite Difference Time Domain (FDTD) algorithm, we can calculate the near field of isolated mask structures efficiently,...
conference paper 2008
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Spronck, J. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
We show the theoretical limitations of a multi-axial nulling interferometer with respect to longitudinal polarization. We furthermore analyze the filtering capabilities of a single-mode fiber in this case.
conference paper 2007
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Spronck, J. (author), Vosteen, L.L.A. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
We present the design of a new testbed experiment to demonstrate nulling interferometry using polarization properties. This three-beam set-up is perfectly symmetric with respect to the number of reflections and transmissions and should therefore allow a high rejection ratio in a wide spectral band.
conference paper 2007
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Spronck, J. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
We present a new type of nulling interferometer that makes use of polarization properties to have on-axis destructive interference. The proposed design, which only involves commercial components and no achromatic device, is also suitable for internal modulation. This type of interferometer should enable a high rejection ratio in a theoretically...
conference paper 2006
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Spronck, J. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
We discuss the previously-reported measurements of a three-beam nulling interferometer without achromatic phase-shifters, using delay lines only. The theoretical rejection ratio of a few thousand has not been achieved experimentally. In order to explain the obtained results, some direct spectral and polarization measurements have been performed....
conference paper 2006
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Van der Avoort, C. (author), Mieremet, A. (author), Pereira, S. (author), Braat, J. (author)
We present results of experiments obtained using a new nulling technique that enables deep nulling without the use of achromatic phase shifters. The experimental set-up consists of a three-beam interferometer that should provide a nulling depth of several thousands over a wavelength range of 500 to 650 nm. The intended depth of null was not...
conference paper 2004
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Montilla, I. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
Wide field interferometry has become a subject of increasing interest in the recent years. New methods have been suggested in order to avoid the drawbacks of the standard wide field method (homothetic mapping) which is not applicable when the aperture is highly diluted; for this reason imaging with non-homothetic arrays is being extensively...
conference paper 2004
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