552 research outputs found

    Generalized optical theorem for reflection, transmission, and extinction of power for scalar fields

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    We present a derivation of the optical theorem that makes it possible to obtain expressions for the extinguished power in a very general class of problems not previously treated. The results are applied to the analysis of the extinction of power by a scatterer in the presence of a lossless half space. Applications to microscopy and tomography are discussed

    Message passing tools for software integration

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    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 95-96).by John C. Carney.M.S

    Near-Field Scanning Optical Tomography: A Nondestructive Method for Three-Dimensional Nanoscale Imaging

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    We present the theoretical foundation for near-field scanning optical tomography, a method for three-dimensional optical imaging with subwavelength resolution. An analysis of the forward problem for both scalar and vector optical fields is described. This is followed by the construction of the pseudoinverse solution to the linearized inverse scattering problem. The results are illustrated by numerical simulations

    Strong Tip Effects in Near-field Scanning Optical Tomography

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    A model for the interaction of the scanning probe in near-field scanning optical microscopy is presented. Multiple scattering of the illuminating field with the probe is taken into account. The implications of this so-called strong tip model for the solution of the associated inverse scattering problem are studied through simulations

    Eikonal Method for Calculation of Coherence Functions

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    A method is presented for computing the cross-spectral density of a special class of partially coherent fields in which the coherent modes obey an eikonal equation. This method allows for statistical analysis of optical systems based on simple ray tracing

    Nanoscale Optical Tomography using Volume-scanning Near-field Microscopy

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    The relationship between sample structure and data in volume-scanning backscattering mode near-field optical microscopy is investigated. It is shown that the three-dimensional structure of a dielectric sample is encoded in the phase and amplitude of the scattered field and that an approximate reconstruction of the sample structure may be obtained

    Generalized optical theorem for reflection, transmission, and extinction of power for electromagnetic fields

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    We present a generalization of the optical theorem for electromagnetic fields. This result is used to obtain the power extinguished from a field by a scatterer contained in a dielectric half space. Applications to microscopy and tomography are described

    Nonlinear Inverse Scattering and Three-Dimensional Near-Field Optical Imaging

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    The nonlinear inverse scattering problem for electromagnetic fields with evanescent components is considered. A solution to this problem is obtained in the form of a functional series expansion. The first term in the expansion corresponds to the pseudoinverse solution to the linearized inverse problem. The higher order terms represent nonlinear corrections to this result. Applications to the problem of three-dimensional optical imaging with subwavelength resolution are described and illustrated with numerical simulations

    Convergence and Stability of the Inverse Scattering Series for Diffuse Waves

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    We analyze the inverse scattering series for diffuse waves in random media. In previous work the inverse series was used to develop fast, direct image reconstruction algorithms in optical tomography. Here we characterize the convergence, stability and approximation error of the serie
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