基于Wollaston棱镜的大角度液晶光束偏转系统

设计了一种能够应用于空间光通信的大角度高精度光束偏转系统。系统采用液晶空间光调制器(LCSLM)实现小角度光束偏转,采用多Wollaston棱镜级联实现角度放大。介绍了LCSLM和Wollaston棱镜的光束偏转原理,并对大角度高精度光束偏转系统进行了仿真分析。仿真结果表明系统能够实现角度范围为±13.25°的光束偏转。国内首次提出运用Wollaston棱镜来实现大角度的光束偏转。     

Birefringent neutron prisms for spin echo scattering angle measurement

In the first decade of the 19th century, an English chemist, William Wollaston, invented an arrangement of birefringent prisms that splits a beam of light into two spatially separated beams with orthogonal polarizations. We have constructed similar devices for neutrons using triangular cross-section solenoids and employed them for Spin Echo Scattering Angle Measurement (SESAME). A key difference between birefringent neutron prisms and their optical analogues is that it is hard to embed the former in a medium which has absolutely no birefringence because this implies the removal of all magnetic fields. We have overcome this problem by using the symmetry properties of the Wollaston neutron prisms and of the overall spin echo arrangement. These symmetries cause a cancellation of Larmor phase aberrations and provide robust coding of neutron scattering angles with simple equipment.     

Wollaston棱镜阵列干涉光谱仪的研制及其光通量的分析

利用空间调制干涉光谱技术研制了基于双层Wollaston棱镜组的干涉仪原理样机,用该样机进行了干涉光谱实验,采集了He-Ne激光器干涉图像,通过对图像进行数据处理,获得了光源的归一化光谱图。并对样机系统做了光通量分析。它与传统的使用单个Wollaston棱镜测量光谱的方法相比,光谱分辨率和光通量可以提高一倍以上。     

一种多棱镜组合设计优化图像干涉性能的新方法

为了在不影响干涉条纹成像质量的基础上通过增大双折射棱镜结构角的方法获得更细致的光谱成分,优化设计了双折射棱镜的结构.通过计算分束角与结构角之间的函数关系,分析得知在传统双折射棱镜后附加一个与第二个楔形同性质的等腰三角形棱镜,使出射棱镜的o光和e光平行于光轴,即分束角α为0°,从而干涉条纹的成像不再受分束角的变化所影响....     

Quasi-common path three-wavelength holographic interferometer based on Wollaston prisms

This article presents a digital three-wavelength holographic interferometer based on the use of two Wollaston prisms. This provides an in-line setup with quasi common-path and as a consequence there is no additional independent reference wave to be added. Thus, immunity to external perturbations such as vibrations or thermal perturbations is achieved. Furthermore, the set-up exhibits a single shot and real time capability which is very useful to study dynamic events. By using the two Wollaston prisms in an astigmatic configuration, spatial carrier frequencies can be adjusted both in amplitude and orientation. The digital hologram processing is based on Fourier processing and filtering around the carrier spatial frequency so that phase shifting is not required. The use of three wavelengths leads to visualizing directly the zero order fringe and regions for which there is no air density variation in a dynamic flow. Experimental proof of concept is demonstrated with a supersonic jet when the injection pressure varies.     

Recent contribution in color interferometry and applications to high-speed flows

Recent improvements brought to color interferometry for analyzing high-speed flows are described through different applications. First, the optical technique based on differential interferometry using a polarized white light and one or two Wollaston prisms allows to record high-speed interferograms of the flow downstream of a circular cylinder. Then, this technique has been applied to axisymmetric flows for studying an interaction between a supersonic hot jet and a coaxial supersonic flow. Another application concerns the study of hypersonic flows using Wollaston prisms with a large birefringence angle. Finally, the analysis of gaseous mixture and the evolution of two-gases interface submitted to an acceleration is presented. Interferograms analysis is made from a modeling of interference fringes versus the optical path difference which allows to easily extract quantitative information of the gas density. In order to obtain absolute measurements of the gas density, real-time holographic interferometry has been developed using a three-color laser source and a panchromatic holographic plate. The technique generates the achromatic white fringe which makes the zero order of interference fringes easy to identify. An application is presented in a 2D subsonic wind tunnel, in which the unsteady wake flow past a cylinder is recorded at high framing rate. In this optical setup, transmission holograms are used. As a conclusion, an approach is proposed to analyze the 3D flows from real-time color holographic interferometry using reflection holograms and the problems to solve are described.     

自适应双频激光准直系统的原理及实验

介绍了一种新型自适应双频激光准直系统，该系统利用两个完全对称的渥拉斯顿棱镜，五个作为测量元件，另一个作为补偿元件。对测量信号的处理，采用比相技术，测量元件可以暂时移出光路，因而能够进行同轴度的测量。两束干涉光基符合共光路原则，适应于长距离的准直测量。     

偏光棱镜性能参量的求解新法

建立了一个共点三轴系统,给出了相应的角参量关系公式,并利用其得到了任意空间角度入射时可调分束角棱镜的分束角公式,证明了此方法在解决与棱镜结构有关的问题时简单有效.     

改型Wollaston棱镜的光程差及其特性分析

简述了改型Wollaston棱镜的偏光结构和分光机理;应用波法线追迹法分析了光在棱镜中的传播规律与波矢轨迹;推导出了任意入射面内、以任意角入射时光在棱镜中的传播方向及出射点坐标;给出了改型Wollaston棱镜中o光和e光光程差的理论表达公式;采用计算机模拟,给出了光程差随入射角、入射面与棱镜主截面的夹角、棱镜结构角及波长的变化曲线,并对其变化特性进行了深入的分析. 该研究对偏光棱镜的理论研究具有普遍的指导意义,为偏振分光器件及干涉成像光谱仪的研制和应用提供了重要的理论依据和实践指导. 关键词： 改型Wollaston棱镜 波法线追迹法 光程差     

基于斯托克斯矢量的偏振成像仪器及其进展

偏振成像技术将景物的偏振信息转化为二维图像信息,从而可以和灰度图像一样对目标景物进行场景特征分析。介绍了基于斯托克斯矢量的偏振成像原理。按照获取斯托克斯矢量方法的不同,分别介绍了偏振片起偏、偏振棱镜分光和可变延迟波片调制三类分时偏振成像方式,分振幅、分孔径、分焦平面三种同时偏振成像方式。结合我国的制造水平,设计了双CCD渥拉斯顿棱镜同时偏振成像实验系统,并采集了实验图像。分析了各种偏振成像方式的优缺点。指出了偏振激光照明主动偏振成像、光谱偏振成像是偏振成像仪器进一步的发展方向。     

基于Wollaston棱镜的图像复分快照式成像光谱仪设计

设计一种以Wollaston棱镜为分光元件的图像复分快照式成像光谱系统,主要包括前置望远物镜、准直镜、Wollaston棱镜组、成像镜和补偿滤光片。此类光学系统可以一次曝光获取同一目标景物在不同波长下的二维信息。光束经过Wollaston棱镜组分光,为了使不同波长对应景物不至于重叠,要求分束角度比较大,这样进入成像镜的光线入射角度相对较大,无疑增加了成像镜的设计难度。分析了基于Wollaston棱镜的图像复分快照式成像光谱仪的原理及特点,设计了一套完整的成像光谱系统。全系统结构复杂,光学系统的光阑必须匹配好。为了使得不仅单个镜头成像质量良好,而且镜组之间能够良好的衔接,将前置望远物镜设计为像方远心结构,准直镜设计为物方远心结构。全系统采用多重结构,使得16个谱段在56线对处的MTF值均接近衍射极限,点列图中RMS值基本都在艾里斑以内,系统成像质量良好。     

Transmission Bragg-grating grisms for pulse compression

We design a grism compressor based on transmission gratings and high refractive index prisms to compensate for both the second- and third-order dispersions of SF57 glass at 800?nm. The use of transmission gratings eases the geometrical constraints, allows a final recombination of the spectral components out of the bulk of the prisms and suggests a potential application of these grims to high-energy pulse compression. The dispersion law of this grism compressor is measured in double-pass configuration and negative third-order dispersion is achieved. We demonstrate efficient operation with an overall throughput >60% over a 100?nm bandwidth.     

Dispersion theory of multiple-prism beam expanders for pulsed dye lasers

The single pass dispersion of multiple-prism beam expanders of interest for practical pulsed dye laser cavities is calculated. The theory is extended to enable evaluation of the overall (outward and return pass) dispersion of multiple-prism-grating combinations. It is found that although the contribution to overall dispersion from the prisms can be minimized (though not eliminated for practical expanders) by arrangement of the prisms in compensating pairs, it is in any case small (≈2%) compared to the contribution to dispersion from the grating in practical cavities. Formulae for dispersion of multiple-prism-grating combinations including up to four prisms arranged in additive or compensating configurations are given; the dispersion of an arbitrary number of prisms arranged in conjunction with a grating can also be calculated. The implications for output linewidth of pulsed dye lasers incorporating prism beam expanders are discussed.     

宽谱段共光轴线色散成像光谱仪三棱镜分光系统设计

针对棱镜型成像光谱仪结构复杂、具有严重的色散不均匀性,进行了共光轴线色散棱镜式宽谱段成像光谱仪研究。利用棱镜的色散公式建立了对称型三棱镜组合分光结构的数学模型,获得了满足直视结构的棱镜组合,并在此基础上分析影响棱镜组色散线性因素：棱镜材料的折射率和色散率对棱镜组线色散影响比较大,入射角度对其影响比较小,并提出改善色散线性的方法,获得了满足线色散要求的棱镜组合的折射率条件,从而为共光轴结构的线色散棱镜式成像光谱仪初始结构的选择提供了重要理论依据。在工作波段为400~1 000 nm、中心波长偏向角为0°、最大色散角为0.6°、光谱仪系统数值孔径NA为0.18、光谱分辨率为5 nm条件下,实现共光轴三棱镜分光系统的线色散设计,最后利用ZEMAX进行了模拟分析表明,理论计算结果与实际仿真结果基本相符。     

Liquid crystalline optical components for application in optical sensing

Manufacturing process of Wollaston prisms using ZLI-1957 Liquid Crystal (LC) mixture and waveplates from RMS03-001 Liquid Crystalline Polymer (LCP) is presented. The Wollaston prism presented in the paper has the splitting angle of 0.37 mrad, and can be used in optical setups where very straight fringes are not required. Produced LCP waveplates exhibit retardation from 175.3 nm to 238.6 nm at the wavelength of 622 nm and show local retardation variations of .     

复合折射棱镜的色散研究

理论分析用二种不同材料组成复合色散棱镜的色散量，提出变相色散棱镜，以增大色散量。结论在实验中得到验证。     

脉冲染料激光振荡器的色散问题

本文通过理论推导给出了脉冲染料激光器由多块不同棱镜构成的扩束系统和光栅组合后多程色散的通用计算公式。同时本文也指出光栅与棱镜组合的正确光路安排,从而加大整个系统的色散,减少输出线宽。     

星载高分辨率超光谱成像仪分光方式的选择

从多个方面分析了棱镜和光栅色散分光的优缺点,分析结果表明棱镜更适于星载高分辨率超光谱成像仪的分光。在透过率方面,棱镜光谱仪透过率高达95.24％(VNIR),而光栅的衍射效率仅为60%~70%。在杂散光方面,棱镜光谱仪的杂散光可达10－4,而光栅的杂散光为10－2。在0.4 －2.5 范围,棱镜光谱仪相对光栅光谱仪有优越性。在色散线性方面,光栅光谱仪基本线性,棱镜光谱仪的短波非线性问题可通过复合棱镜进行补偿。可靠性方面,棱镜光谱仪较光栅光谱仪有优势;在光谱带宽和成本方面,棱镜光谱仪与光栅光谱仪基本接近。     

基于组合Wollaston棱镜成像光谱仪的视场扩大原理分析

论述了视场扩大型成像光谱仪的核心部件——组合Wollaston棱镜的结构和分光机理;应用波法线追迹法分析了光在任意方位入射面内,以任意角入射时组合Wollaston棱镜中的波矢传播规律;推导出了光在棱镜中的传播方向及出射点坐标;给出了传播过程中e光和o光之间光程差的理论表达式;采用计算机模拟,给出了光程差随入射角和入射面方位角的变化曲线;在此基础上对组合Wollaston棱镜扩大光谱仪视场的原理进行了深入分析和讨论.上述研究对偏振干涉成像光谱技术的理论研究与技术创新,对自行设计的稳态大视场偏振干涉成像光谱 关键词： Wollaston棱镜 偏振干涉成像光谱仪 波法线追迹法 视场扩大原理     

棱镜对色散补偿系统的时域ABCD矩阵分析方法

讨论了棱镜对的负色散效应,利用时域ABCD矩阵方法分析了高斯型光脉冲经棱镜对色散补偿系统的脉宽和啁啾的变化,指出输出光脉冲的脉宽是展宽还是压缩,与棱镜啁啾、棱镜间距和光脉冲在棱镜中传输的距离的取值有关.讨论了棱镜对色散补偿系统对脉冲压缩的最佳条件,指出此时输出光脉冲脉宽随棱镜啁啾的增大而骤减,且骤减程度随啁啾增大而逐渐削弱,最后趋于一稳定值.