为了对模拟溢油样品在不同偏振态激发下诱导荧光的偏振特性进行研究, 借鉴了穆勒矩阵椭偏仪的原理和结构, 搭建了基于旋转波片原理的模拟溢油样品激光诱导荧光椭偏实验装置。 通过特征值校准方法对该装置进行校准, 获得了宽波段下偏振状态调制矩阵W(λ)和偏振状态分析矩阵A(λ)的确切调制状态, 并基于荧光光谱强度矩阵Flu(λ)分别建立了轻、 中、 重质原油样品和柴油样品的荧光穆勒矩阵。 通过极化分解方法对荧光穆勒矩阵进行分解后发现, 不同样品荧光光谱的退偏振性质差异十分显著。 柴油样品荧光穆勒矩阵的退偏振系数Δ(λ)没有明显的波长响应性, 在荧光光谱范围内始终保持较高的退偏值, 而三种原油样品的退偏系数Δ(λ)则随波长增大逐渐上升, 其中, 中质原油样品退偏系数随波长的变化幅度小于重质样品, 超过轻质样品; 就不同样品的退偏值来看, 轻质原油样品最高, 重质样品最低, 中质原油样品介于二者之间, 柴油样品的荧光退偏值略低于轻质原油样品, 介于轻质和中质原油样品之间。 将基于荧光穆勒矩阵极化分解后的结果与线偏振激发下样品荧光光谱的正交偏振实验结果进行对比, 发现两种实验方法获得的退偏系数具有较高的吻合程度。 实验还发现, 四种模拟溢油样品荧光穆勒矩阵所包含的双向衰减和相位延迟性质都很微弱, 不具有明显的差异。

By refering to the principle and structure of the Mueller matrix ellipsometry, a LIF ellipsometric setup with rotating waveplate was built up to investigate the polarization characterization of laser-induced fluorescence from the simulated oil spill samples under excitation of laser with different elliptical polarization states. The setup was calibrated with the Eigenvalue Calibration Method at first to obtain the exact modulation states of both the polarization modulation matrix W(λ) and the polarization analyses matrix A(λ). Then with the fluorescence intensity matrices Flu(λ) measured by sequentially modulation of the polarization-state generator unit and the polarization-state analyzer unit, LIF Mueller matrices of light, medium and heavy crude oil samples as well as diesel were established and analyzed via polar decomposition. It was found that the depolarization properties of fluorescence spectrum from different samples were of significant differences. The depolarization coefficient extracted from the LIF Mueller matrix from diesel varied little with the wavelength increasing, which maintained a high degree of depolarization value within the whole spectral range, while those from other three crude samples kept rising under the same circumstances. With respect to the variation amplitude of the depolarization coefficient, the medium crude sample exceeded the heavy crude but was inferior to the light one. Among the four simulated oil samples, the depolarization coefficient extracted from LIF Mueller matrices from light crude and heavy crude samples were highest and lowest respectively, while those from diesel and medium samples lied between them. Compared to the results of LIF orthogonal polarization experiment under linearly polarized excitation, the depolarization coefficients Δ(λ) extracted from polar decomposition of LIF Mueller matrices were highly relevant to those DODP obtained from orthogonal polarization characterization of fluorescence spectrum of the simulated oil samples. And it was also found that both the diattenuation and retardation properties of the fluorescence spectrum from the simulated oil samples were very weak and showed little differences.