共查询到19条相似文献,搜索用时 62 毫秒
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考虑不透明漫射基底的反射/发射和半透明介质层的吸收/发射,建立半透明介质层表面红外测温过程的辐射传输模型,采用反向蒙特卡罗法进行模拟,获得探测表面在热像仪的指示辐射温度。与不透明表面红外测温进行比较,分析表面形状、基底发射率ε_s及介质层光学厚度τ的影响。结果表明,半透明介质层表面的指示辐射温度在ε_s1.0时,随τ的增大而增大,τ≥2时数值趋于ε_s=1.0时的结果,与不透明表面存在较大差异;针对复杂形状或内凹曲面红外测温,不透明表面和半透明介质层表面均受到反射其他部位辐射现象的影响。 相似文献
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半透明梯度折射率介质内辐射熵传递方程及其数值模拟 总被引:1,自引:0,他引:1
在非相干辐射条件下,基于Planck光谱辐射熵强度定义,导出半透明梯度折射率介质内光谱辐射熵传递方程,以及局部辐射熵产率理论表达式.基于离散坐标法对辐射熵传递方程进行数值求解.以一维半透明梯度介质平板为例,对辐射熵方程及其算法进行验证.平板整体无因次辐射熵产的计算结果与宏观热力学定律的结果一致. 相似文献
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对具有一维高斯分布粗糙表面的半透明介质层光谱散射,基于微面斜率法建立了考虑遮蔽效应的粗糙表面光谱辐射传递概率模型,采用蒙特卡罗法模拟光谱辐射能束在粗糙表面、半透明介质层介质与镜反射基底之间的多次反射、折射和吸收等传递过程。通过数值模拟,分析了介质层表面粗糙度、光谱光学厚度、折射率和基底反射率对介质层双向反射分布函数(BRDF)的影响。结果表明,表面粗糙程度不同时,反射峰值随入射角度呈现不同的变化趋势;表面粗糙度增加或折射率增大都将导致漫反射份额增大;介质层光谱光学厚度和基底反射率主要影响BRDF的数值大小,而对BRDF的分布形态影响很小。 相似文献
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负折射率介质层中光波的相位和传输特性研究 总被引:13,自引:0,他引:13
针对在理解负折射率材料中光波的传播特性时相位的特殊性质 ,详细分析推证了负折射率介质中折射率、波矢k的大小和方向、空间坐标系以及波相相位互之间的关系。分析结果表明负折射率介质层中的波矢k的反常取向是由于其标量值为负 ;在统一的坐标系下 ,由该标量值参与数值计算和分析 ,k则由标量值和单位矢量k0 (k0 >0 )共同决定 ,而不必再考虑左、右手系的区别。在此基础上依据电磁场理论推导了光波在负折射率介质层中的传输矩阵 ,用以分析含有负折射率介质层的复杂薄膜系统的光学性质。初步计算结果显示含有负折射率介质层的膜系对TE和TM波的光谱特性都有显著改变 相似文献
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变折射率介质中光线追迹通用算法的研究 总被引:8,自引:2,他引:8
基于几何光学的光线折射和反射原理提出了变折射率介质中的光线追迹算法,给出了在光线追迹过程中进行递推的反射光线和折射光线的方向余弦方程;解决了空间中法线的确定和光线回转等问题。最后通过对多种不同的存在解析解的特殊折射率分布的数值解值和解析解值的比较,验证了算法的正确性,并且讨论了应用算法时应该注意的问题和算法中还有待解决的问题。该算法不但具有广泛的适用性,基本不受折射率分布的制约,而且其数值解精度达10^-5。该算法在变折射率介质的光学设计和空间成像补偿等方面有着广阔的应用前景。 相似文献
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C. K. Duan 《光谱学快报》2013,46(2):237-246
Two macroscopic models for the dependence of the spontaneous emission rate of luminescent ions or nanoparticles embedded in dielectric media of various optical refractive indexes are presented. The available experimental results on the spontaneous emission rate (lifetime) are examined using the two models. A simple criterion for how to choose the proper model for a given system is summarized. 相似文献
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Dmitri Toptygin 《Journal of fluorescence》2003,13(3):201-219
It is well known that the probabilities of radiative transitions in a medium differ from those in vacuum. Excitation of a fluorescent molecule and its radiative decay are examples of radiative transitions. The rates of these processes in solution depend on the optical characteristics of the solvent. In this article the radiative decay rate and the extinction coefficient of a fluorescent molecule in solution are expressed in terms of the intrinsic properties of the fluorescent molecule (electronic transition moments) and the optical characteristics of the solvent (refractive index, group velocity of light). It is shown that the group velocity does not enter in the final expressions for the radiative decay rate and the extinction coefficient; this means that the dispersion of the refractive index has no effect on these quantities. The expressions for both the radiative decay rate and the extinction coefficient contain the refractive index of the solvent and the local field correction factor. The latter depends on the cavity model, and, for some cavity models, on the shape of the cavity. Four types of cavity models are discussed; for each model the limits of applicability are examined. Experimental evidence in support of specific cavity models is reviewed. 相似文献
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Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction frequency band, while both the bistability and multi-stability can occur in the positive refraction frequency bands. Therefore, optical bistability can be realized from conventional material to negative index material due to quantum coherence in our scheme. 相似文献
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位相型全息记录介质的浮雕深度和折射率变化的测量方法 总被引:3,自引:0,他引:3
本文提出了一种直接测量位相型全息记录介质的浮雕深度和折射率改变量的方法,它利用干涉显微镜及带CCD摄像头的微机组成的简单系统,可获得很高的测量精度。本文分析了测量误差以及为使系统保持最高测量精度而应选取的最佳测量条件。 相似文献
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应用等效粒子近似方法研究了光学空间孤子在带有局域和非局域非线性横向非均匀介质中的传输动力学行为.发现孤子在传播过程中横向的周期性振荡.折射率调制幅度和波导的归一化宽度决定了振荡周期的大小.介质的非局域对振荡振幅有着较小的影响.模拟了孤子传输过程,所得数值结果与理论分析符合很好.此外,模拟传输还发现多孤子束缚态能够在这个模型中稳定传播.这种振荡特性或许可以应用于光学路由器、转换器、开关等. 相似文献
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Zhichao Wang Qiang Cheng Guihua Wang Huaichun Zhou 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(18):2835-2845
This paper extends the DRESOR (Distribution of Ratios of Energy Scattered by the medium Or Reflected by the boundary surface) method to radiative transfer in a variable refractive index medium. In this method, the intensity is obtained from the source term along the curved integration paths determined only by the variable refractive index, and the DRESOR values are calculated by the Monte Carlo method in which the propagation of the energy bundles are affected by Snell's law. With given temperatures on the black boundaries of a one-dimensional medium, the temperature distribution inside the medium with a variable scattering property is calculated under the condition of radiative equilibrium. It is shown that the DRESOR method has a good accuracy in the cases studied. For an isotropic-scattering medium with the same optical thickness, the scattering albedo has no effect on the temperature distribution, which can be obtained from the general equations and can be seen as an extension of what exists for a constant refractive index; however, the different refractive index causes obvious changes in the temperatures inside the medium. The effect of anisotropic scattering on the temperature distribution cannot be ignored, although it is still weaker than the effect caused by variation in the refractive index. 相似文献