Searched for:
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document
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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Van Haver, S. (author), Braat, J.J.M. (author), Janssen, A.J.E.M. (author), Janssen, O.T.A. (author), Pereira, S.F. (author)
We present details of a novel imaging algorithm based on the extended Nijboer–Zernike (ENZ) theory of diffraction. We derive integral expressions relating the electric field distribution in the entrance pupil of an optical system to the electric field in its focal region. The evaluation of these integrals is made possible by means of a highly...
journal article 2009
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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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Van der Avoort, C. (author), Pereira, S.F. (author), Braat, J.J.M. (author), Den Herder, J.W. (author)
In optical aperture-synthesis imaging of stellar objects, different beam combination strategies are used and proposed. Coaxial Michelson interferometers are very common and a homothetic multiaxial interferometer is recently realized in the Large Binocular Telescope. Laboratory experiments have demonstrated the working principles of two new...
journal article 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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Spronck, J. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
We introduce a new concept of nulling interferometer without any achromatic device, using polarization properties of light. This type of interferometer should enable a high rejection ratio in a theoretically unlimited spectral band. We analyze several consequences of the proposed design, notably, the possibility of fast internal modulation.
journal article 2006
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Spronck, J. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
We introduce the concept of chromatism compensation in nulling interferometry that enables a high rejection ratio in a wide spectral band. Therefore the achromaticity condition considered in most nulling interferometers can be relaxed. We show that this chromatism compensation cannot be applied to a two-beam nulling interferometer, and we make...
journal article 2006
document
Van De Nes, A.S. (author), Braat, J.J.M. (author), Pereira, S.F. (author)
journal article 2006
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Braat, J.J.M. (author), Nugrowati, A.M. (author), Van de Nes, A.S. (author), Pereira, S.F. (author)
Poster presentation Optics Research Group TU Delft
journal article 2005
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Montilla, I. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
A new interferometric technique for Michelson wide-field interferometry is presented that consists of a Michelson pupil-plane combination scheme in which a wide field of view can be achieved in one shot. This technique uses a stair-shaped mirror in the intermediate image plane of each telescope in the array, allowing for simultaneous correction...
journal article 2005
document
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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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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Wang, H. (author), Groen, F.H. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
We present an analysis of the reading capability of a novel optical pickup consisting of a single-mode and a multi-mode rectangular waveguide. According to the simulations, if one has prior information about the structure of the disk, superresolution readout could be achieved. The proposed system has the advantage to be compact and should be...
conference paper 2004
document
Musa, S. (author), Pereira, S.F. (author), Braat, J.J.M. (author), Fransoo, F. (author), Van Thourhout, D. (author), Baets, R. (author)
We present a study on the use of optical waveguides in readout units for optical recording. Optical waveguides can be used to increase the storage capacity of optical recording, which is limited by diffraction. Optical waveguides are attractive for application in readout units of optical recording systems because it is possible to make compact...
conference paper 2004
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Wang, H. (author), Groen, F.H. (author), Pereira, S.F. (author), Braat, J.J.M. (author)
In photonics, light usually diffracts in all directions when it emerges from a planar optical waveguide. Besides this fact, in this letter we show that a waveguide with a rectangular cross section can be turned to a focusing system by using three-dimensional self-imaging technique. We obtained a configuration where the focus of the field lies...
journal article 2003
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