The Experts below are selected from a list of 8007 Experts worldwide ranked by ideXlab platform
Anthony Harness - One of the best experts on this subject based on the ideXlab platform.
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implementing non scalar diffraction in Fourier Optics via the braunbek method
Optics Express, 2020Co-Authors: Anthony HarnessAbstract:Fourier Optics is a powerful and efficient tool for solving many diffraction problems, but relies on the assumption of scalar diffraction theory and ignores the three-dimensional structure and material properties of the diffracting element. Recent experiments of sub-scale starshade external occulters revealed that the inclusion of these physical properties is necessary to explain the observed diffraction at 10-10 of the incident light intensity. Here, we present a methodology for implementing non-scalar diffraction while maintaining the efficiency and ease of standard Fourier Optics techniques. Our methodology is based on that of Braunbek, in which the Kirchhoff boundary values are replaced with the exact field in a narrow seam surrounding the edge of the diffracting element. In this paper, we derive the diffraction equations used to implement non-scalar diffraction and outline the computational implementation used to solve those equations. We also provide experimental results that demonstrate our model can replicate the observational signatures of non-scalar diffraction in sub-scale starshades, in effect validating our model to better than 10-10 in relative intensity. We believe this method to be an efficient tool for including additional physics to the models of coronagraphs and other optical systems in which a full electromagnetic solution is intractable.
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Implementing non-scalar diffraction in Fourier Optics via the Braunbek method
Optics express, 2020Co-Authors: Anthony HarnessAbstract:Fourier Optics is a powerful and efficient tool for solving many diffraction problems, but relies on the assumption of scalar diffraction theory and ignores the three-dimensional structure and material properties of the diffracting element. Recent experiments of sub-scale starshade external occulters revealed that the inclusion of these physical properties is necessary to explain the observed diffraction at 1e-10 of the incident light intensity. Here, we present a methodology for implementing non-scalar diffraction while maintaining the efficiency and ease of standard Fourier Optics techniques. Our methodology is based on that of Braunbek, in which the Kirchhoff boundary values are replaced with the exact field in a narrow seam surrounding the edge of the diffracting element. In this paper, we derive the diffraction equations used to implement non-scalar diffraction and outline the computational implementation used to solve those equations. We also provide experimental results that demonstrate our model can replicate the observational signatures of non-scalar diffraction in sub-scale starshades, in effect validating our model to better than 1e-10 in relative intensity. We believe this method to be an efficient tool for including additional physics to the models of coronagraphs and other optical systems in which a full electromagnetic solution is intractable.
Giovanni Mana - One of the best experts on this subject based on the ideXlab platform.
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A Fourier Optics approach to the dynamical theory of X-ray diffraction--continuously deformed crystals.
Acta Crystallographica Section A Foundations of Crystallography, 2004Co-Authors: Giovanni Mana, Carlo PalmisanoAbstract:X-ray diffraction in continuously deformed crystals is considered by application of Fourier Optics and from the viewpoint of the analogy between X-ray dynamics and the motion of two-level systems in quantum mechanics. Different forms of Takagi's equations are traced back to a common framework and it is shown that they are different ways to represent the same propagation equation. A novel way to solve Takagi's equations in the presence of a constant strain gradient is presented and approximation methods derived from quantum mechanics are considered. Crystal deformation in X-ray interferometry and two-crystal spectrometry are discussed and it is demonstrated that Si lattice-parameter measurements depend on the diffracting plane spacing on the crystal surface.
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A Fourier Optics approach to the dynamical theory of X-ray diffraction--perfect crystals.
Acta crystallographica. Section A Foundations of crystallography, 2003Co-Authors: Giovanni Mana, Francesco MontanariAbstract:A new formalism is presented concerning the dynamics of X-rays in crystals. It is based on Takagi's equations and Fourier Optics; it also offers an alternative to the usual Ewald-von Laue approach. The article does not give new results but shows a new way to formulate the dynamical theory of X-ray diffraction. In addition, it proposes a novel description of X-ray propagation based on the analogy between the dynamics of X-rays in crystals and that of two-level quantum systems.
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A Fourier Optics model of two-beam scanning laser interferometers
The European Physical Journal D - Atomic Molecular and Optical Physics, 1999Co-Authors: A. Bergamin, G. Cavagnero, L. Cordiali, Giovanni ManaAbstract:The article illustrates the use of Fourier Optics to describe the operation of two-beam scanning laser interferometers. It deals with the effect of diffraction on the spatial periodicity of a monochromatic and coherent beam. Particular attention is given to the analysis of systematic errors in high-accuracy laser metrology. The article reviews the special case of plane wave and Gaussian illuminations, examines how beam truncation affects the period of traveling fringes and presents a general relation between the relative wavelength deviation and the impulse standard deviation of the photons.
Hakan Urey - One of the best experts on this subject based on the ideXlab platform.
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Fourier Optics analysis of grating sensors with tilt errors
Optics Letters, 2011Co-Authors: Onur Ferhanoglu, Fatih M Toy, Hakan UreyAbstract:Dynamic diffraction gratings can be microfabricated with precision and offer extremely sensitive displacement measurements and light intensity modulation. The effect of pure translation of the moving part of the grating on diffracted order intensities is well known. This study focuses on the parameters that limit the intensity and the contrast of the interference. The effects of grating duty cycle, mirror reflectivities, sensor tilt and detector size are investigated using Fourier Optics theory and Gaussian beam Optics. Analytical findings reveal that fringe visibility becomes <0.3 when the optical path variation exceeds half the wavelength within the grating interferometer. The fringe visibility can be compensated by monitoring the interfering portion of the diffracted order light only through detector size reduction in the expense of optical power. Experiments were conducted with a grating interferometer that resulted in an eightfold increase in fringe visibility with reduced detector size, which is in agreement with theory. Findings show that diffraction grating readout principle is not limited to translating sensors but also can be used for sensors with tilt or other deflection modes.
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Fourier Optics analysis of grating sensors with tilt errors.
Optics letters, 2011Co-Authors: Onur Ferhanoglu, M. Fatih Toy, Hakan UreyAbstract:Dynamic diffraction gratings can be microfabricated with precision and offer extremely sensitive displacement measurements and light intensity modulation. The effect of pure translation of the moving part of the grating on diffracted order intensities is well known. This study focuses on the parameters that limit the intensity and the contrast of the interference. The effects of grating duty cycle, mirror reflectivities, sensor tilt and detector size are investigated using Fourier Optics theory and Gaussian beam Optics. Analytical findings reveal that fringe visibility becomes
Maksim Skorobogatiy - One of the best experts on this subject based on the ideXlab platform.
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Exploiting k-space/frequency duality in Fourier Optics toward real-time compression-less terahertz imaging
Computational Imaging III, 2018Co-Authors: Hichem Guerboukha, Kathirvel Nallappan, Maksim SkorobogatiyAbstract:We present a theoretical formulation and an experimental demonstration of a fast compression-less terahertz imaging technique based on broadband Fourier Optics. The technique exploits k-vector/frequency duality in Fourier Optics which allows to use a single-pixel detector to perform angular scan along a circular path, while the broadband spectrum is used to scan along the radial dimension in Fourier domain. The proposed compression-less image reconstruction technique (hybrid inverse transform) requires only a small number of measurements that scales linearly with the image linear size, thus promising real-time acquisition of high-resolution THz images. We develop an algorithm based on a polar formulation of the Fourier transform to reconstruct the image. First, we show how the equations are transformed when passing from a spatial integral to a frequency integral. Second, we analytically demonstrate that, in the case of binary amplitude objects and phase objects, the reconstructed image from our formulation is proportional to the original object. Third, we experimentally demonstrate the image reconstruction method in the two above-mentioned cases: we use a metal aperture for the binary object and an engraving in a polymer sample for the phase object. A detailed analysis of the novel technique advantages and limitations is presented, and its place among other existing THz imaging techniques is clearly identified.
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Exploiting k-space - frequency duality in Fourier Optics towards real-time compression-less terahertz imaging
arXiv: Optics, 2017Co-Authors: Hichem Guerboukha, Kathirvel Nallappan, Maksim SkorobogatiyAbstract:We present theoretical formulation and experimental demonstration of a novel technique for the fast compression-less terahertz imaging based on the broadband Fourier Optics. The technique exploits k-vector/frequency duality in Fourier Optics which allows using a single-pixel detector to perform angular scan along a circular path, while the broadband spectrum is used to scan along the radial dimension in Fourier domain. The proposed compression-less image reconstruction technique (hybrid inverse transform) requires only a small number of measurements that scales linearly with the image linear size, thus promising real-time acquisition of high-resolution THz images. Additionally, our imaging technique handles equally well and on the equal theoretical footing the amplitude contrast and the phase contrast images, which makes this technique useful for many practical applications. A detailed analysis of the novel technique advantages and limitations is presented, as well as its place among other existing THz imaging techniques is clearly identified
Francesco Montanari - One of the best experts on this subject based on the ideXlab platform.
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A Fourier Optics approach to the dynamical theory of X-ray diffraction--perfect crystals.
Acta crystallographica. Section A Foundations of crystallography, 2003Co-Authors: Giovanni Mana, Francesco MontanariAbstract:A new formalism is presented concerning the dynamics of X-rays in crystals. It is based on Takagi's equations and Fourier Optics; it also offers an alternative to the usual Ewald-von Laue approach. The article does not give new results but shows a new way to formulate the dynamical theory of X-ray diffraction. In addition, it proposes a novel description of X-ray propagation based on the analogy between the dynamics of X-rays in crystals and that of two-level quantum systems.