稳态大视场偏振干涉成像光谱仪中视场补偿型Savart偏光镜透射率研究

论述了基于视场补偿型Savart偏光镜的稳态大视场偏振干涉成像光谱仪的分光机理.依据电磁场边值条件,分析了光在视场补偿型Savart偏光镜中各晶体分界面上的透射情况,得出了透射率的理论计算公式.采用计算机模拟,分析了在半波片为不同材料时,透射率随入射波长、视场角及半波片厚度的变化关系.研究表明,视场补偿型Savart偏光镜具有大视场、高通量、高探测灵敏度的显著特点.此研究可为新型干涉成像光谱技术的研究和新型偏振干涉成像光谱仪的设计、研制提供重要的理论指导. 关键词： 偏振干涉成像光谱仪 视场补偿型Savart偏光镜 透射率 电磁场边值条件     

新型偏振干涉成像光谱仪中Savart偏光镜透射率的研究

Savart偏光镜是自行研制的新型稳态偏振干涉成像光谱仪中的核心部件，阐述了该Savart偏光镜的分光机理.基于电磁场边值条件，分析了入射面与Savart偏光镜左板主截面重合及垂直时，光透过Savart偏光镜各界面的反射和折射，得出了各界面透射系数的表达式以及Savart偏光镜透射率的理论计算公式.采用计算机模拟，给出了Savart偏光镜透射率随视场角和波长的变化曲线，并与研制的Savart偏光镜实验测试结果进行了分析比较，两者变化规律相符. 表明该Savart偏光镜具有大视场、高通量的显著特点，适宜作为静态干涉仪和稳态偏振干涉成像光谱仪的高效横向剪切分束器. 这为新型偏振干涉成像光谱技术的研究以及仪器研制提供了重要的理论依据.     

The coefficients of reflection and refraction on interface of the crystals in the Savart polariscope

According to the boundary conditions of the electromagnetic field, the coefficients of reflection and refraction on the interface of crystal in the Savart polariscope are obtained for ordinary ray (o-ray) and extraordinary ray (e-ray).The coefficients of reflection and refraction are different from an isotropic medium and have more complicated forms than isotropic medium.     

The double reflection on the interface of uniaxial crystals in the Savart polariscope

The reflection in the Savart polariscope is different from the isotropic medium. The double reflection of rays in the Savart polariscope is analyzed and discussed on the basis of the Snell law. The double reflection formulae of the extraordinary ray and the ordinary ray are given. These results may provide a theoretical and practical guide for studying, developing and engineering polarization interference imaging spectrometers. Supported by the National Natural Science Foundation of China (Grant Nos. 40375010 and 60278019), the Science and Technology Plan Foundation of Shaanxi Province (Grant No. 2005K04-G18), and the Special Research Project of Shaanxi Provincial Educational Department (Grant No. 07JK261)     

Relationship between incident angle and dispersion in static large field of view polarization interference imaging spectrometer

The static large field of the view polarization interference imaging spectrometer is based on the modified Savart polariscope. There appears a dispersion between the ordinary ray and extraordinary ray when light passes through the modified Savart polariscope. The dispersion greatly influences the intensities and the results of the interferogram and target image in the static large field of the view polarization interference imaging spectrometer. At the same time, the incident angle determines the dispersion. When the light goes through the modified Savart polariscope, the dispersion occurs in the left plate, the half-wave plate and the right plate of the modified Savart polariscope. Using the extension of Snell's law, the dispersion in the crystal is theoretically calculated and numerically simulated separately. The relationship curve between incident angle and the dispersion is obtained by simulation.     

Analysis of the lateral displacement and optical path difference in wide-field-of-view polarization interference imaging spectrometer

The mechanism of beam splitting and principle of wide-field-of-view compensation of modified Savart polariscope in the wide-field-of-view polarization interference imaging spectrometer (WPIIS) are analyzed and discussed. Formulas for the lateral displacement and optical path difference (OPD) produced by the modified Savart polariscope are derived by ray-tracing method. The theoretical and practical guidance is thereby provided for the study, design, modulation, experiment and engineering of the polarization interference imaging spectrometers and other birefringent Fourier-transform spectrometers based on Savart polariscopes.     

A simple and effective model for Jones matrix to evaluate the transmission performance of Savart polariscope

Starting from the wave normal tracing treatment in the Savart polariscope that relates the Jones matrix to its transmission performance,this paper establishes a simple and effective model for the Jones matrix at an arbitrary inci-dence in the spatial domain.Analytical expressions of all the matrix components are determined with the consideration of all the main impact factors.This model needs only a few parameters hence it is convenient to be employed to evaluate the propagation performance of any birefringent optical system.The simulated results obtained with it demonstrate that this model gives a precise representation of the characteristic of light propagation in the Savart polariscope.This would provide useful suggestions for the design,calibration,and performance improvement of any other birefringent polarisation element and optical system.     

Cosmic rays in the heliosphere

Summary This is a rapporteur paper for the XXIV International Cosmic-Ray Conference covering topics of anomalous cosmic rays, shock acceleration, modulation and transport theory, cosmic-ray gradients, corotating interaction regions, coronal-mass ejections, and solar neutrinos. Among the highlights of the meeting are —conclusive proof that most anomalous cosmic rays are singly charged,—undisputed detection of anomalous cosmic-ray hydrogen,—discovery of unexpectedly large anisotropies of pickup ions,—observation of pronounced solar rotational modulation of cosmic-ray fluxes to the highest heliolatitudes (∼80°) probed by the Ulysses spacecraft, and—new measurements of modulation effects sensitive to particle charge sign. Rapporteur talk given at the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Cosmic rays at the highest energies

Cosmic rays at the highest energies are observed with the Pierre Auger Observatory. Recent results are discussed and the properties of high-energy cosmic rays are reviewed.     

基于双折射晶体的快拍穆勒矩阵成像测偏原理分析

针对传统穆勒矩阵成像测偏仪包含活动部件,需进行多次测量,容易产生测量误差,不能对运动目标或动态场景进行同时、实时测量等问题,提出了一种以改进型萨瓦偏光镜为核心分光器件的快拍Mueller矩阵成像测偏技术(MSP-SMMIP).它不含任何活动部件,能通过单次快拍测量获取目标强度图像和全部16个穆勒矩阵阵元图像.它主要由偏振态产生和偏振态分析两部分组成,偏振干涉条纹通过偏振态产生光路后定位于测试样品上,随后这些条纹通过空间载频将样品的Mueller矩阵分量编码,经偏振态分析光路成像于焦平面上.采用斯托克斯矢量-穆勒矩阵形式阐明了光场偏振态被MSP-SMMIP调制的过程,给出了其像面干涉图表达式,讨论了Mueller矩阵反演和系统定标的方法.基于CCD相机参数分析了系统的光学指标.通过数值模拟实验给出模拟测量结果,通过定性和定量评价测量结果表明该系统的可行性.MSP-SMMIP技术具有稳态、快拍、结构简洁、易定标、可同时实时获取目标强度图像和全部Mueller矩阵阵元图像的显著特点.     

新型双通道差分偏振干涉成像系统

针对Wollaston棱镜和Savart偏光镜(SP)组合的差分成像光谱系统存在光线溢出和无法改变系统光程等问题,设计了一种新型双通道差分偏振干涉成像系统.此系统不仅可获取正交偏振图像,还可以通过调整Savart偏光镜的厚度来改变系统光程.介绍了该系统的结构、理论原理,并利用琼斯矩阵推导出四束偏振光线的复振幅及其相干光干涉强度表达式.分析了宽视场Savart偏光镜(WSP)和可调光程的Savart偏光镜(MSP)的分束特性,得出WSP相较于SP具有更好的剪切能力和WSP可优化系统光路的结论.获得了不同楔形结构角下MSP的光程差、横向剪切量随楔形移动量的变化曲线.通过实验验证,获取了不同剪切量下的干涉图像和复色光下平行、垂直分量的空间图像,进而获得了总的强度图像和差分强度图像.得出差分强度图像相较于偏振强度图像具有较高对比度的结论.研究结果对双通道成像光谱系统的性能优化具有一定的参考意义.     

Ultra-high energy cosmic rays and prompt TeV gamma rays from gamma ray bursts

Gamma ray bursts (GRBs) have been proposed as one possible class of sources of the ultrahigh energy cosmic ray (UHECR) events observed up to energies ≳ 10²⁰ eV. The synchrotron radiation of the highest energy protons accelerated within the GRB source should produce gamma rays up to TeV energies. Here we briefly discuss the implications on the energetics of the GRB from the point of view of the detectability of the prompt TeV γ-rays of proton-synchrotron origin in GRBs in the up-coming ICECUBE muon detector in the south pole.     

The diffuse cosmic gamma rays

A careful and objective analysis is made of the available experimental observations which claim evidence for the existence of a shoulder in the spectrum of the diffuse cosmic gamma rays in the energy range of 1–40 MeV. In this, special cognisance is taken of the experimental data and theoretical calculations of the Bombay Group. These considerations cast serious doubts on the reliability of the high flux values obtained by many experimenters in this energy region emphasizing thereby the need for great caution in interpreting the shoulder as due to cosmological effects with far reaching implications.     

干涉成像光谱仪光通量的计算与分析

论述了干涉成像光谱技术的工作原理,采用光线追迹的方法对基于Sagnac棱镜和Savart偏光镜的干涉仪中的光线传播规律进行了分析,推导出了无狭缝式干涉成像光谱仪光通量的精确理论计算公式,并对干涉成像光谱仪中具有代表性的Savart型偏振干涉成像光谱仪光通量和改型Sagnac成像光谱仪光通量进行了分析比较.通过计算机模拟给出了系统光通量随入射角和波长变化的关系曲线.该研究对干涉成像光谱仪的研究和工程化研制具有重要的指导意义. 关键词： 干涉成像光谱仪 光通量 透射比     

Atmospheric gamma rays in the energy region 40–1000 GeV

A large stack of lead-emulsion sandwich detector assembly was flown over Hyderabad, India. High energy gamma rays at the float altitude were unambiguously identified from the cascades they induced, and their energies reliably determined by improved methods. From an analysis of 163 gamma rays of energy ≳ 30 GeV, it is found that the differential energy spectrum is represented by the power lawJ _r (E)= 129·4E ^{−2·62±0·12} photons m⁻² sr⁻¹sec⁻¹ GeV⁻¹ at an effective atmospheric depth of 14·3 g cm⁻²; this is the first reliable balloon measurement of atmospheric gamma rays in the energy range 40–1000 GeV. After correcting for the gamma rays radiated by the primary cosmic ray electrons, the production spectrum of gamma rays, resulting from the collisions of cosmic ray nuclei with air nuclei, at the top of the atmosphere isP _r (E, 0)=8·2 × 10⁻⁴ E^2.60±0.09 photons g⁻¹sr⁻¹sec⁻¹ GeV⁻¹. The atmospheric propagation of the electromagnetic component due to the cascade process is also derived from the gamma ray production spectrum.     

Speckle shearing interferometer using a Savart plate

We describe a speckle shearing interferometer using a Savart polariscope. The purpose of this interferometer is to obtain the derivative of the out-of-plane displacement suffered by a scattering surface when put under stress. This information is useful to know the bending moments. The setup is compact, very stable, and does not require any stringent adjustment.     

Features of the refraction of glancing light rays from optically less dense absorbing media

A study is made of the refraction of glancing light rays at the interface of two optically homogeneous media, one of which is absorbing. Experimental data indicate an increase by several times in the flux of the refracted rays in the case of refraction of glancing rays from absorbing slabs. It is shown that the dispersion zone of deflection of the light rays partly transmits glancing rays in a transparent slab and can be opaque in weakly absorbing slabs. It is established that the increase in the intensity of the refracted beams is due to the more effective transformation of the glancing rays moving in the dispersion zone into refracted rays. Data are available on the dependence of the refracted flux on the relative refractive index.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 57–60, March, 1981.I thank V. E. Zuev, S. D. Tvorogov, and M. V. Kabanov for their interest in the work and discussion of the results.     

On the biological effects of cosmic rays: Epidemiological studies

Summary Determining the biological effects of cosmic rays and other natural ionizing radiations, could possibly help us in shedding light on the more general problem of low-dose ionizing-radiation effects. In this work we provide a survey of the most recent studies available on epidemiological methods: we discuss the main difficulties in using these methods, as well as the discrepancies in their results. Work presented as a poster at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

宇宙射线对面阵CCD器件的伤害及预防措施

研究了宇宙射线对面阵 CCD传感器的冲击伤害及产生白疵点的原因 ,并对宇宙射线冲击的物理现象作了初步的说明。针对生产 CCD传感器的单位 ,给出了实验统计数据 ,并提出了可供参考的预防措施。     

Cosmic rays from the knee to the highest energies

This review summarizes recent developments in the understanding of high-energy cosmic rays. It focuses on galactic and presumably extragalactic particles in the energy range from the knee (10¹⁵ eV ) up to the highest energies observed (>10²⁰ eV). Emphasis is put on observational results, their interpretation, and the global picture of cosmic rays that has emerged during the last decade.