| Project/Area Number |
06650044
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | Hokkaido University |
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Principal Investigator |
ASAKURA Toshimitsu Hokkaido University, Research Institute for Electronic Science, Professor, 電子科学研究所, 教授 (70001188)
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| Co-Investigator(Kenkyū-buntansha) |
OKAMOTO Takashi Hokkaido University, Research Institute for Electronic Science, Research Associa, 電子科学研究所, 助手 (40204036)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Multiple scattering / Backscattering / Weak localization of light / Coherence / Fractal / Dynamic light scattering / Brownian motion / Long range correlation / 粒子懸濁液 / 二波長相関 / 流速計測 |
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| Research Abstract |
The aim of the project is to reveal the statistical properties of coherent light multiply scattered by highly disordered media and to develop new techniques for extracting information about the structure and motion of multiple scattering objects.
(1) Enhanced backscattering of light : The effects of the spatial coherence of incident light, the size of particles suspended in the medium, and the polarization direction of scatteredlight, on the enhanced backscattering peak were investigated theoretically and experimentally. All these parameters were found to influence strongly the shape and peak value of the enhancement. The temporal fluctuations of scattered light due to Brownian motion of particles were also evaluated, and a characteristic behavior was found for the light scattered exactly in the backward direction.
(2) Multiple scattering from fractal media : Light scattered by mass-fractal random media exhibits properties that are different from those of homogeneous random media. It was
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shown that the shape of the backscattering peak peculiar to the fractal medium is formed by its characteristic scattering free-path distribution of photons inthe medium. This feature can be utilized to measure the fractal dimension of multiple scattering objects. The intensity of ballistic light was also found to provide information about the fractal structure.
(3) New phenomena on strong multiple scattering : Computer simulations were performed to investigate the spatiotemporal properties of light scattered from strong scattering media in Which the waves in the medium interferewith each other at scattering points. Some new phenomena, such as contrast enhancement of the forward-scattered light intensity and negative spatial intensity correlation of the backscattered light, were revealed and their physical origins were elucidated using the crossing probability of photon path trajectories .
(4) Spectral correlation methodfor fluid velocimetry : The cross-correlations of scattered light intensities with different wavelengths were measured using concentrated flowing microspheres undergoing Brownian motion. It was shown that the correlation time measured by the spectral correlation method is unaffected by the Brownian motion, its reciprocal values being proportional to the flowing velocity of the scattering medium. A new technique for velocity measurement was proposed which is applicable to dense colloidal media. Less
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