本文選題：后向漫散射穆勒矩陣 + 偏振成像　； 參考：《華中科技大學》2005年碩士論文

【摘要】：當把一束準直的偏振光束聚焦,垂直入射到介質表面時,測量入射點周圍區(qū)域的后向漫散射光偏振態(tài)和強度的空間分布模式,分析區(qū)域內每點的位置與該點的后向漫散射光偏振態(tài)、強度的函數(shù)關系,就可以確定介質的約化散射系數(shù)和吸收系數(shù)等光學特性參量。進一步分析,還可以獲得介質的各向異性因子和散射粒子平均大小等信息。當入射光的偏振態(tài)不同時,混濁介質的后向漫散射光的強度空間分布模式也不同。因此引入穆勒矩陣形式可以全面的描述混濁介質的后向漫散射特性,通過穆勒矩陣可以計算出任意偏振態(tài)入射光情況下,混濁介質的后向漫散射光的斯托克斯矢量。本文對混濁介質的后向漫散射穆勒矩陣的測量進行研究,主要內容包括: 借用斯托克斯矢量-穆勒矩陣這種數(shù)學形式來描述偏振光束和混濁介質的后向散射特性,并結合龐加球闡述了這種形式的物理意義。通過穆勒矩陣運算推導出任意光束的斯托克斯矢量測量方法,然后在光的斯托克斯矢量測量的基礎上,完成穆勒矩陣的測量原理的推導。 基于推導出的測量原理設計并實現(xiàn)了一套實驗系統(tǒng)用于測量混濁介質的后向漫散射穆勒矩陣。在系統(tǒng)中,激光被調制成所需偏振態(tài),聚焦于混濁介質表面。然后利用CCD 相機配合相應的偏振元件,測量入射點周圍區(qū)域的后向散射光中特定偏振態(tài)的能量空間分布,并由測量值計算出介質的后向漫散射穆勒矩陣。 從光路、光源和CCD 相機三個方面對系統(tǒng)的各部分性能進行了詳盡的分析,并利用系統(tǒng)分別對消偏振分光棱鏡的反射穆勒矩陣和濃度1.5%的脂肪乳溶液的后向漫散射穆勒矩陣進行了測量。實驗證明,本系統(tǒng)不僅能夠有效地分離混濁介質的漫后向散射光和表面鏡面反射光,排除鏡面反射光的干擾,而且測量得到圖像中所有點均由介質的漫后向散射光所成像得到,不存在無效像素。在消除測量中散斑的負面影響時,延長CCD 相機曝光時間地辦法也被實踐證明是非常有效的。因此利用本實驗系統(tǒng)能夠準確地測量混濁介質的后向漫散射穆勒矩陣,且能夠用于生物組織的偏振特性的研究。
[Abstract]:When a collimated polarized beam is focused on the surface of the medium, the polarization state and the spatial distribution of the intensity of the diffuse scattering light in the region around the incident point are measured. By analyzing the function relationship between the position of each point in the region and the polarization state and intensity of the backscattered light, the optical characteristic parameters such as the reduced scattering coefficient and the absorption coefficient of the medium can be determined. Further analysis, the anisotropy factor and the average size of scattering particles can be obtained. When the polarization state of the incident light is different, the spatial distribution mode of the diffuse backscattering light in the turbid medium is also different. Therefore, the Muller matrix form can be used to describe the diffuse backscattering characteristics of turbid media. By using Muller matrix, the Stokes vector of diffuse backscattering light can be calculated for arbitrary polarized incident light. The measurement of diffuse backscattering Muller matrix in turbid media is studied in this paper. The main contents are as follows: The Stokes vector-Muller matrix is used to describe the backscattering characteristics of polarized light beams and turbid media, and the physical meaning of this form is explained with the Poincare sphere. The Stokes vector measurement method of arbitrary beam is derived by using Muller matrix operation, and then the principle of Moeller matrix measurement is deduced on the basis of Stokes vector measurement of light. Based on the derived measurement principle, a set of experimental system is designed and implemented to measure the diffuse backscattering Muller matrix in turbid media. In the system, the laser is modulated to the desired polarization state and focused on the surface of the turbid medium. Then the energy spatial distribution of the specific polarization states in the backscattering region around the incident point is measured by using the CCD camera and the corresponding polarizing elements. The diffuse scattering Muller matrix of the medium is calculated from the measured values. The performance of each part of the system is analyzed in detail from three aspects: optical path, light source and CCD camera. The reflectance Muller matrix of depolarization splitter prism and the backscatter Muller matrix of 1.5% fat emulsion solution were measured by the system. Experimental results show that the system can not only effectively separate diffuse scattering light from surface reflection light and eliminate the interference of mirror reflection light, but also measure all points in the image by the diffuse scattering light of the medium. There are no invalid pixels. The method of prolonging the exposure time of CCD camera has also been proved to be very effective in eliminating the negative effect of speckle in measurement. Therefore, this experimental system can accurately measure the diffuse backscattering Muller matrix of turbid media and can be used to study the polarization characteristics of biological tissues.
【學位授予單位】：華中科技大學
【學位級別】：碩士
【學位授予年份】：2005
【分類號】：R311

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相關期刊論文 前2條

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2 聶守平,陳延如,趙琦;復合粒子場散射特性的Mueller矩陣表示[J];激光雜志;2001年04期

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本文編號：1788845