Modern spectroscopy methods in studying sctructure and function of biopolymers in biology and medicine

Presentations

Vision and acoustical imaging in non-uniform media

Svet V.D.

Institute of Acoustics, 4 Shvernik St. 117036, Russia +7 495 126 90 35, e-mail: vsvetd@mail.ru

Real environments where objects are settled down are non-uniform and they are the source of many physical problems of acoustical imaging. In non-uniform environments there can be scattering, refraction, multi reflections of sound waves from borders, other types of acoustic waves and dispersion. These effects not only worsen quality of acoustic images, but often do impossible reception of acoustic images Occurrence and wide use of physical or electronic lenses (beamforming), which are the key elements of any imaging system in optics, radio and acoustics, is obliged to the development of optics of uniform mediums which in turn, has old biological preconditions. However the comparison of lens imaging with vision apparatus of vertebrate animals encounters its "strange" design: the retina of these animals is inverted, and optical image formed by a lens, is projected on photoreceptors through layers of nervous cells. The model of such vision apparatus completely corresponds to many practical applications of acoustical imaging, for example, to ultrasonic transcranial diagnostics: transducer and object are separated from each other by cranial bone of non-uniform thickness which does impossible acoustical imaging of brain structures. The paradoxicality of this analogy consists that in lens imaging systems specialists try to exclude or compensate the influence of a non-uniform layer, and the nature during evolution for any reasons has entered a non-uniform layer in visual lens apparatus. Calculations show, that at normal sight non-uniform retina layers can cause so strong scattering of light, that the image being projected on photoreceptors is completely destroyed.

Two groups of methods of image reconstruction in non-uniform environments are considered, and the basic attention is given to nonlinear phase methods as unlike methods of the first group, wave front inversion by matched filtering processing, they do not require detailed knowledge of parameters of the non-uniform medium.

The analysis of nonlinear phase methods of reconstruction of acoustic images and neurophysiologic and morphological features of vision has allowed not only to offer the possible mechanism of image processing in primary system of the vision analyzer, but also to reveal some additional opportunities of nonlinear methods of acoustical imaging in nonuniform environments.

V. Svet, N. Zuikova. Phase fluctuations and acoustical images.// Acoustics of non-uniform mediums. Moscow: Institute of Acoustics, 2003, 14-28

V. D. Svet. Possible Physical Principles of Image Transformation in an Inverted Eye Retina // Doklady Physics 51, 7, (2006). Pp 339-343 ( Translated from Doklady Akademii Nauk, 409, 7, 2006)

V. Svet, A. Khazen . About image transformations in the inverted eye retina // Biophysics. 2007 (under publishing)

Real environments where objects are settled down are non-uniform and they are the source of many physical problems of acoustical imaging. In non-uniform environments there can be scattering, refraction, multi reflections of sound waves from borders, other types of acoustic waves and dispersion. These effects not only worsen quality of acoustic images, but often do impossible reception of acoustic images Occurrence and wide use of physical or electronic lenses (beamforming), which are the key elements of any imaging system in optics, radio and acoustics, is obliged to the development of optics of uniform mediums which in turn, has old biological preconditions. However the comparison of lens imaging with vision apparatus of vertebrate animals encounters its "strange" design: the retina of these animals is inverted, and optical image formed by a lens, is projected on photoreceptors through layers of nervous cells. The model of such vision apparatus completely corresponds to many practical applications of acoustical imaging, for example, to ultrasonic transcranial diagnostics: transducer and object are separated from each other by cranial bone of non-uniform thickness which does impossible acoustical imaging of brain structures. The paradoxicality of this analogy consists that in lens imaging systems specialists try to exclude or compensate the influence of a non-uniform layer, and the nature during evolution for any reasons has entered a non-uniform layer in visual lens apparatus. Calculations show, that at normal sight non-uniform retina layers can cause so strong scattering of light, that the image being projected on photoreceptors is completely destroyed. Two groups of methods of image reconstruction in non-uniform environments are considered, and the basic attention is given to nonlinear phase methods as unlike methods of the first group, wave front inversion by matched filtering processing, they do not require detailed knowledge of parameters of the non-uniform medium. The analysis of nonlinear phase methods of reconstruction of acoustic images and neurophysiologic and morphological features of vision has allowed not only to offer the possible mechanism of image processing in primary system of the vision analyzer, but also to reveal some additional opportunities of nonlinear methods of acoustical imaging in non-uniform environments.

V. Svet, N. Zuikova. Phase fluctuations and acoustical images.// Acoustics of non-uniform mediums. Moscow: Institute of Acoustics, 2003, 14-28

V. D. Svet. Possible Physical Principles of Image Transformation in an Inverted Eye Retina // Doklady Physics 51, 7, (2006). Pp 339-343 ( Translated from Doklady Akademii Nauk, 409, 7, 2006)

V. Svet, A. Khazen . About image transformations in the inverted eye retina // Biophysics. 2007 (under publishing)

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