非圆柱形发散梯度折射率棒透镜光线传播轨迹的解析解族

本文研究光线在具有非圆柱形等折射率面的发散型梯度折射率棒透镜中的传播规律,提出在轴向弱非匀条件(即dg~(-1)(z)/dz<<1下近轴子午光线轨迹的一种解析表达式.从该解析式的解析解,棒透镜梯度参数g(z)所满足的条件出发,导出棒透镜的折射率分布族.文中给出了两个线性无关的光线传播轨迹的解析解族,并以一种发散型棒透镜为例讨论了近轴成像特性.     

梯度折射率球透镜的制备及其光线轨迹测试

自麦克斯韦鱼眼透镜理论模型提出后,长期以来学术界一直以为它只是一种绝对光学仪器,在实践中并没有应用的可能。但通过对麦克斯韦鱼眼微球透镜的理论研究表明,在一定条件下,它具有良好的成像性能和耦合效率。根据菲克定律推导出梯度折射率球透镜的折射率分布函数。并且熔制了含Li+硅酸盐玻璃和采用槽沉法以及Na+/Li+离子交换法制备直径为0.3—3.0mm的梯度折射率球透镜。通过干涉法测得了梯度折射率球透镜的折射率分布曲线,并研究了光线通过梯度折射率球透镜的轨迹。研究结果表明:在590℃,离子扩散系数为3.07×10-6mm2/s;所制备的梯度折射率球透镜的折射率分布是抛物线分布,并且和理论分析相吻合;梯度折射率球透镜的光线轨迹满足椭圆方程。     

一种基于恒星光线偏折的大气折射率估计方法

基于标准大气环境的大气折射率理论模型不能反映实际大气折射率的波动性,针对该问题,提出了一种基于恒星光线偏折的大气折射率估计方法。基于光学卫星的恒星观测数据,分析恒星光线经大气折射发生偏折的现象,建立恒星光线经大气折射后进入光学卫星传感器的光路模型,在分层球形大气的假设下证明该光路模型的对称性。研究一种利用恒星实测光线和恒星理论光线迭代前向反馈的方法,用以估计分层大气折射率。最后,利用光学卫星的恒星观测数据进行有效性验证,计算出的大气折射率与理论大气折射率相符,且能够反映短期波动性。对测试用的恒星实测数据进行处理,结果表明:88%以上的恒星理论视线与实测视线的估计值相差不超过1%,其余部分观测数据估计偏差基本不超过20%。     

单轴晶体和各向同性介质交界面上e光光线的折射

根据光在各向异性介质中遵从的Ｆｅｒｍａｔ 原理,较系统地讨论了单轴晶体和各向同性介质交界面上的ｅ 光（ 非常光） 光线的折射,得到了光轴在任意取向情况下的折射基本公式。同时给出一般情况下确定ｅ 光线折射角的具体解。在此基础上对几种特殊的光轴取向给予了较详细的讨论。最后讨论了ｅ 光线的折射公式与ｅ 光波法线的折射定律的等价性,从而说明Ｆｅｒｍａｔ 原理与光的电磁波理论存在内在的一致性。     

双轴晶体光轴角的计算

通过坐标变换把折射率椭球方程x~2/n_1~2 y~2/n_2~2 z~2/n_3~2=1从主介电坐标系Oxyz转换到另一个新的坐标系Ox′y′z′中,这个新的坐标系Ox′y′z′可以通过将坐标系Oxyz绕原点旋转得到.只要使新的折射率椭球方程与x′y′平面的交线是一个圆,就可以确定z′轴就是晶体的光轴.由此得出了双轴晶体光轴角的计算公式.     

变折射率介质中光线追迹通用算法的研究

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。     

任意折射率的三维离散空间光线追迹方法研究

介绍了Runge-Kutta光线追迹方法,并以此作为任意折射率介质中光线追迹基本手段;针对具有折射率任意分布性质并且离散的三维流场空间,建立了流场空间任意点的折射率和折射率梯度计算方法;在追迹过程中,提出了追迹步长根据当地折射率梯度和网格几何尺寸自适应调节的思想和方法,用于提高追迹的精度和效率。结果表明,建立的光线追迹方法适用于三维离散空间折射率任意分布的光线追迹,具有较高的精度和效率。     

光线在恒星表面附近传播的偏折角

光线在恒星附近传播时,理论计算的偏折角有两个结果.一个结果由Newton引力论计算而得,另一个由Einstein广义相对论计算得到.后者是前者的两倍.对于与人类最近的恒星太阳,数值计算结果分别为0.875″(角秒)和1.75″,本文给出这两个结果的详细计算过程.日食发生时是检测理论结果的良好时机,迄今为止所有的实验观测结果支持相对论对太阳光线偏折角的计算.     

星载激光测高系统的大气折射延迟改正模型研究

星载激光测高仪通过测量从卫星平台发射的激光脉冲在卫星与地面激光脚点之间的渡越时间计算两者之间的距离。由于光束经过大气层时发生的折射,导致卫星激光测高系统典型的与大气延迟相关的测距误差在数米量级。讨论了大气折射延迟修正的理论与方法,分析比较了各种大气折射率模型,以全球首个对地观测星栽激光测高仪系统GLAS系统为例,给出了各种折射率模型的计算偏差,发现在常见温度和湿度范围内Owens375模型是一种精度较高的简化折射率模型;计算了GLAS系统高度角偏离天顶方向不超过10°的情况下,使用简单映射函数与CfA2．2映射函数模型的值,发现其差异不超过0．5mm。     

Isotropie focusing of light rays in cosmology

It is shown that if the past light cone of an observer is isotropic and has a caustic (i.e., contains points which are conjugate to the observer along a null geodesic) then the spacetime admits a compact (S³) spacelike hypersurface. The result is valid for space-times with dimension 4.     

三棱镜偏向角与入射角关系的研究

根据三棱镜偏向角与入射角的关系,讨论了最小偏向角和最小入射角,为实验中掌握出射光线的移动规律,准确判断最小偏向角的位置提供了理论依据.     

On the energy spectrum of light nuclei in primary cosmic rays

The energy spectrum of primary protons and α particles has been determined from analysis of the EAS MSU array data. The result of the analysis is compared with the corresponding data from other arrays.     

Implications on the origin of cosmic rays in light of 10 TV spectral softenings

Precise measurements of the energy spectra of cosmic rays(CRs)show various kinds of features deviating from single power-laws,which give very interesting and important implications on their origin and propagation.Previous measurements from a few balloon and space experiments indicate the existence of spectral softenings around 10 TV for protons(and probably also for Helium nuclei).Very recently,the DArk Matter Particle Explorer(DAMPE)measurement about the proton spectrum clearly reveals such a softening with a high significance.Here we study the implications of these new measurements,as well as the groundbased indirect measurements,on the origin of CRs.We find that a single component of CRs fails to fit the spectral softening and the air shower experiment data simultaneously.In the framework of multiple components,we discuss two possible scenarios,the multiple source population scenario and the background plus nearby source scenario.Both scenarios give reasonable fits to the wide-band data from TeV to 100 PeV energies.Considering the anisotropy observations,the nearby source model is favored.     

地闪通道底部回击速度的频变特性分析

回击通道的光学观测对于研究回击发展过程和物理机制、完善工程回击模型都具有重要的意义。采用雷电发展过程高速光学观测系统（LiPOS）测量了人工引雷中距离通道底部21 m至309 m的一组通道发光波形,基于系统辨识的输出误差（OE）模型建立了回击向上传播过程光辐射脉冲间的传递函数,获得了1 kHz～1 MHz频段内群速度和相速度曲线。时域分析表明,通道辐射光脉冲波形前沿上升时间由靠近底部的1.1 μs变化为309 m高度处的1.84 μs,色散特性是其变化的重要原因。频域分析表明,OE模型能够有效抑制测量噪声的影响、获得清晰的分析曲线,100 kHz以下低频段内群速度呈显著的非单调变化,500 kHz以上区域群速度稳定在58%光速左右。将分析结果与相关文献的研究进行了对比和讨论。研究结果对于定量评价回击电流传播色散特性具有重要参考价值。     

3D heliospheric simulations of cosmic rays in the light of Ulysses

Summary Recent Ulysses observations in the polar regions of the heliosphere have provided fundamental new insights into the modes of cosmic-ray transport in the heliosphere. Ulysses discovered variations in the magnetic field which are large enough to produce significant cosmic-ray effects, and which are consistent with a previous prediction. In addition to impeding the inward, radial diffusive and drift access of cosmic rays over the poles as discussed previously, the magnetic fluctuations imply a significantly larger latitudinal diffusion. These effects directly lead to both a much reduced latitudinal gradient and significant 27-day time variations near the pole. We conclude that the general picture of cosmic-ray transport and modulation developed over the past decade, with reasonable parameters, can account for most of the observed global, large-scale phenomena. Paper presented at the Special Session on the Ulysses mission of the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Effect of turning of rays on scattering of light in a layered medium

The problem of the scattering of light by random inhomogeneities in a layered medium whose characteristic scale is large compared to the wavelength of light is considered. The attention is mainly focused on the effect that the turning of incident and scattered waves has on light scattering in such a medium. In the mixed (q _⊥, z) Fourier representation, expressions for normal waves, and Green’s function are found, which can be used both far from the turning point, where the fields are described in the WKB approximation, and near this point, where the fields are described using the Airy function. Based on these expressions and using the Kirchhoff method, a general expression for the scattering intensity in the far field of the sample is obtained, which takes into account the turning of the incident and scattered waves in the fluctuating medium. Physical consequences of the calculation results are analyzed. In particular, it is shown that even a comparatively small gradient of the refractive index in the layer leads to a rather appreciable redistribution of the scattering intensity between the forward and backward hemispheres. In this case, the shape of the scattering indicatrix is rather exotic with sharp discontinuities, peaks, and dips whose amplitude is on the order of the intensity itself. Original Russian Text ? A.Yu. Val’kov, A.A. Zhukov, V.P. Romanov, 2008, published in Optika i Spektroskopiya, 2008, Vol. 105, No. 4, pp. 647–666.