The model of intermediately rough surface as the specific anti-reflection layer is presented for explaining the coloring of the regular component of a white-light beam forward scattered by a colorless glass with such surface. It is shown that this model predicts the sequence of colors of the forward scattered component of a white-light beam that is observed in practice. New experimental arguments supported this approach are provided.
Keywords: induced spectral changes, rough surfaces, anti-reflection coatings

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It is shown that, for an incoherent superposition of the orthogonally polarized laser beams, the vector singularities of a specific type arise at the transversal cross section of a paraxial combined beam instead of common singularities, such as amplitude zeros or optical vortices (inherent in scalar, i.e. homogeneously polarized, fields), and C points, where polarization is circular, and L lines, along which polarization is linear (inherent in completely coherent vector, i.e. inhomogeneously polarized fields). There are U lines (closed or closing at infinity) along which the degree of polarization equals zero and the state of polarization is undetermined, and isolated P points where the degree of polarization equals unity and the state of polarization is determined by the non-vanishing component of the combined beam. U surfaces and P lines correspond to such singularities in three dimensions, by analogy with L surfaces and C lines in three-dimensional completely coherent vector fields. P lines directly reflect the snake-like distortions of a wavefront of the singular component of the combined beam. Crossing of the U line (surface) is accompanied by a step-like change of the state of polarization onto the orthogonal one. U and P singularities are adequately described in terms of the complex degree of polarization with the representation at the Stokes space, namely at and inside of the Poincar´e sphere. The conditions of topological stability of U and P singularities are discussed, as well as the peculiarities of the spatial distribution of the degree of polarization in the closest vicinity to such singularities. Experimental examples of reconstruction of the combined beam’s vector skeleton formed by U and P singularities as the extrema of the complex degree of polarization are given. Comparison with the related investigations is provided.
Keywords: optical singularities, partial polarization, partial coherence, Stokes polarimetry

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Chizh I., Afonchyna N. Eye Refractometry by the Modified Foucault-knife Method. – Innovations and Technologies News, Nr.3(11), 2011, Latvia.

The modified Foucault-knife method is a new direction in the ophthalmological refractometry for eye ametropy and astigmatism determination. The principal advantages of this method are relative simplicity of hardware and mathematical algorithm and low cost price. It also gives the potential possibility for the reconstruction of the wave aberration function by usage of the isodiopter zones images, video-recorded at the pupil plane.

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The influence of random errors in measurement of eye transverse aberrations on the accuracy of reconstructing wave aberration as well as ametropia (mean power) and astigmatism parameters is investigated. The dependence of mentioned errors on a ratio between the number of measurement points and the number of polynomial coefficients is found for different pupil location of measurement points. Recommendations are proposed for setting these ratios.
Key words: wave-front deformation, eye transverse aberrations, Zernike polynomials, least-squares technique, astigmatism,
errors.

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The influence eye micromotions on the accuracy of estimation of Zernike coefficients from eye transverse aberration measurements was investigated. By computer modeling, the following frequently found eye aberrations have been examined: defocusing, primary astigmatism, spherical aberration of the 3rd and the 5th orders, as well as their combinations. It was determined that the standard deviation of estimated Zernike coefficients is proportional to the standard deviation of angular eye movements. Eye micromotions cause the estimation errors of Zernike coefficients of present aberrations and produce the appearance of Zernike coefficients of aberrations, absent in the eye. When solely defocusing is present, the biggest errors, cased be eye micromotions, are obtained for aberrations like coma and astigmatism. In comparison with other aberrations, spherical aberration of the 3rd and the 5th orders evokes the greatest increase of the standard deviation of other Zernike coefficients.
Key words: eye micromotions, wave-front deformation, eye transverse aberrations, Zernike polynomials, astigmatism, spherical aberration, spatially resolved refractometer.

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