Dissertation
Dissertation > Mathematical sciences and chemical > Mathematics > Applied Mathematics

The Properties of Laser Speckle Based on the Mathematical Morphology

Author FanLingLing
Tutor LiZuo
School Fujian Normal University
Course Optics
Keywords laser speckle mathematical morphology average speckle size scattering coefficient exposure time polarization-difference
CLC O29
Type Master's thesis
Year 2011
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The laser speckle study aroused the interest of many people because of the invention of the laser after 1960s. The laser speckle phenomenon has received much more attention in recent years. In this paper,we processed laser speckle patterns of different concentration samples in the cases of transmission and reflection using mathematical Morphological particle size analysis method. and visually verified that speckles have multi-scale feature. We also found the relationship among average speckle particle size、scattering coefficient and the exposure time, the actual results and the theoretical conclusions have a good match throughthe theoretical analysis.The speckle size obtained by mathematical morphology particle size analysis method can overcome two issues of the speckle description:1. the description of speckle size the traditional method of is not intuitive, not taking into account the morphological characteristics of the speckle;2. In practice, the speckle does not exist strictly fractal.The speckle noise must exist in the coherent polarization-gating imaging. Removal of the speckle noise from the polarization images is of utmost importance in image processing and analysis. In the laser polarimetric imaging, the speckle noise is usually dealt with by multiply averaging a sequence of N captures and rotating waveplate. However, almost all conventional noise removal algorithms mentioned above do not take care of the shapes of objects or features presented in the imaging.The other significative work in this paper is a novel speckle that combines the polarization gating with the morphological opening operation for imaging the absorption inhomogeneities and characterizing the background turbid medium. The results experimentally demonstrate that the polarization gating could remove the diffusive background, and the morphological opening could significantly suppress the speckle noise on the visualization the inhomogeneous objects in optically scattering medium. Furthermore, the average granulometric size is related to the scattering coefficient of background turbid media. Thus, this technique could be a potential tool for medical diagnosis in the future.

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