Searched for: collection%3Air
(1 - 14 of 14)
document
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
document
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
document
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
document
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
document
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
Swinkels, B.L. (author), Bhattacharya, N. (author), Braat, J.J.M. (author)
Absolute distance measurements can be performed with an interferometric method that uses only a single tunable laser. This method has one major drawback, because a small target movement of the order of one wavelength during a measurement will be interpreted as a movement of one synthetic wavelength. This effect is usually mitigated by adding a...
journal article 2005
document
Van der Avoort, C. (author), Den Herder, J.W. (author), Braat, J. (author)
This paper compares two well-known types of interferometer arrays for optical aperture synthesis. An analytical model for both types describes the expected output, in terms of photon counts. The goal is to characterize the performance of both types of array for blind imaging of a wide-field or extended object that would be partially resolved by...
conference paper 2005
document
Krieg, M.L. (author), Braat, J.J.M. (author)
A previously reported interferometer without intermediate optics is used to perform measurements on an aspherical extreme ultraviolet lithography mirror substrate. Acousto-optic modulation based phase shifting is used together with a novel phase retrieval algorithm to retrieve the phase distribution from our interferograms. The phase...
conference paper 2005
document
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
Van der Avoort, C. (author), Van Brug, H. (author), Den Herder, J.W. (author), d'Arcio, L. (author), Le Poole, R. (author), Braat, J. (author)
Homothetic mapping is an aperture synthesis technique that allows interferometric imaging over a wide fieldof-view. A laboratory experiment was set up to demonstrate the feasibility of this technique. Here, we present the first static experiments on homothetic mapping that have been done on the Delft Testbed for Interferometry (DTI). Before a...
conference paper 2004
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
document
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
document
Krieg, M.L. (author), Braat, J.J.M. (author)
This paper will illustrate several approaches to retrieving the shape of aspherical reflective surfaces as used in EUV Lithography, from measurements from a previously reported angstrom-accuracy interferometer. First, the working principles of the interferometer will be reviewed, and typical measurement data expected from the instrument will be...
conference paper 2004
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