用于LED光源准直的紧凑型光学系统设计

设计了一种光学系统,用于发光二极管(LED)光源准直,并通过TracePro软件仿真进行了验证。该系统采取了折射和反射式自由曲面的组合,使LED光源的发散角从70°减少到约4°,效率在约85%,系统的高度为7.65mm,口径为8.73mm。分析了折射和反射的最佳分界角区域是41°～45°,最佳分角比例因子是0.4～0.5。     

大功率半导体激光束非球面准直系统的优化设计

为实现空间激光束的远距离传输,利用矢量折射定理研究了大功率半导体激光器发散光束经非球面、非轴对称准直系统的光传输特性。对空间光线传输得出了矩阵传递公式,并针对大功率线源半导体激光器的发散光束进行了高精度的准直优化设计。为实现对激光束的进一步准直,利用光学设计软件CODE-V设计了卡塞格伦光学天线。利用两点法对发散角进行了实验测试,结果表明优化设计的准直系统发散角为1.924 mrad,经光学天线进一步准直后的发散角为96.2μrad。本空间光线追迹方法对复杂光学系统的精确计算具有一定参考意义,所设计的大功率线源激光束准直系统能广泛应用于远距离激光通信系统中。     

Nondestructive measurement for arbitrary RIP distribution of optical fiber preforms

A nondestructive method is presented to determine simultaneously the refractive index profile and the cross section geometry of optical fiber preforms. An improved formula for calculating the optical path length from the deflection function is derived. The preform is rotated through 180/spl deg/ and the deflection angle data collected, then the back projection technique and linear interpolation algorithm are used in the computed tomographic two-dimensional (2-D) profile reconstruction for preforms of nonuniform cross section. To minimize the computing time, the spatial Nyquist frequency is analytically used to estimate the angle sampling number of views and the numbers of points per scan in advance. Numerical simulations and experimental results show that using 180/spl deg/ angle of view deflection data, accurate preform index distribution reconstructions are obtained.     

基于3D定位的光纤棒内部缺陷检测方法

为检测和定位光纤预制棒的内部缺陷并提高精度,提出一种光线追踪实现3D精确定位的线激光旋转扫描检测方法。利用光散射原理和暗场成像技术,成像设备采集光纤棒每个旋转角纵截面上缺陷的散射光;原始图像经过图像预处理和图像分割获取缺陷的二维信息;基于折射定律和光线追踪建立缺陷的精确定位模型,消除光纤棒表面折射带来的成像位置偏差;最后经过坐标转换、三维建模和三维连通域提取实现缺陷在光纤棒内部的3D定位。实验结果表明:120 W像素的工业相机在旋转角步长为0.9°的条件下,对大尺寸的光纤棒内部缺陷检测轴向定位精度为0.28 mm,径向定位精度为1.05 mm,可实现准确、自动化地检测和定位光纤棒的内部缺陷,为光纤棒的质检和指导光纤拉丝提供重要依据。     

Measurement of stresses in optical fibre or preform

The stress distribution in the cross-section of an optical fibre or preform is measured based on the principle of the Abel transform. It is also shown that the axial stress component has the same shape as that of the refractive index profile of the preform.     

一种红外多光谱成像光学系统设计

介绍了一种中波段的多光谱成像光学系统,由于窄带滤光片对光线入射角度有严格要求,故在光学系统中窄带滤光片的放置位置尤为重要.光学系统由三部分构成,分别为光束压缩单元、分光单元和成像单元,光线经过光束压缩单元口径压缩,但各个视场仍然保持平行光状态,入射到窄带滤光片上的角度均小于7°,满足窄带滤光片的最小入射角要求,最后经过成像单元成像在制冷型中波探测器上.通过细分光谱可以很好的提高目标识别能力.     

Application of focusing method of index profiling to transition region of optical fibre preform

The letter shows how the focusing method of measuring the refractive-index profile of an optical fibre preform can be modified to be applicable to the transition region of the preform. This involves adding a slit between the collimated source and the preform and measuring the scattered power distribution along the projection of the slit in the measurement plane.     

拍星残差数据相关性分析的大气折光差修正

靶场通常采用夜间静态拍星的方式检测光电经纬仪的静态测角总误差。受大气折射率变化的影响,俯仰方向测角数据通常采用大气折光差经验公式进行修正。不同地区和时间的大气环境差异使得该经验公式存在较大误差,导致拍星解算得到的俯仰方向测角误差偏大,且影响俯仰方向测角误差因素的进一步分离。为此,提出了一种基于多台光电经纬仪同步拍星数据相关性分析的大气折光差修正方法。基于经纬仪拍星方位角和俯仰角测量残差模型推导得到了大气折光差修正误差模型。根据该误差模型,利用分布在同一区域不同点位的多台光电经纬仪拍星俯仰角残差数据,采用最小二乘法拟合得到大气折光差的修正系数并修正俯仰角测量残差数据。实测数据表明：采用该方法对俯仰角测量残差进行大气折光差修正后,光电经纬仪俯仰角测角总误差显著降低,且由垂直轴倾斜误差修正错误引起的方位角和俯仰角残差特性得以显现。文中提出的方法无需使用探空气球等获取大气参数,即可对同一地域分布的多台光电经纬仪拍星俯仰角残差数据进行修正,修正后的数据可用于进一步分离其他误差因素,具有较强的工程应用价值。     

Negative refraction in a Si-polymer photonic Crystal membrane

We have observed negative refraction in a photonic crystal (PC) membrane structure at near-infrared wavelengths. The device is fabricated on a silicon-on-insulator substrate and consists of a silicon rod matrix suspended in a polymer where optical energy is delivered by ridge waveguides with various incident angles. The propagation direction inside the PC shows extraordinary refraction with an angle consistent with our two-dimensional numerical simulations. To our knowledge, this is the first experimental observation of isotropic negative refraction in a Si-based planar PC structure at optical frequencies. The realization of negative refraction in a planar Si-based system enables applications in negative index imaging to be integrated into compact optical circuits.     

俯仰角大气折射误差修正方法

针对光学测量系统测量得到的空中目标俯仰角数据,包含了大气折射带来的误差问题,建立了俯仰角修正误差模型,并详细介绍了修正模型具体计算实施过程,提出了采用三弯矩方程计算任意高度大气折射系数和高斯积分计算俯仰角折射修正值．经俯仰角折射效果分析和实践证明该方法精确、有效,满足高精度数据处理的要求．     

浅析大尺寸光纤预制棒(OVD法)的制备工艺

光纤预制棒的大型化是降低光纤拉丝成本的必要手段,本文介绍了利用OVD法生产大尺寸光纤预制棒的工艺方法,主要包括大尺寸光纤预制棒在沉积、烧结、保温过程中的设备与工艺介绍.     

二维各向异性随机介质内光波模式的特性研究

通过建立能够描述各向异性介电常数变化情况的二维随机介质模型,利用时域有限差分法联立求解随机介质中光波所满足的Maxwell方程和激光速率方程,研究了各向异性散射增益材料中的随机激光辐射现象。结果表明随机介质中各向异性散射颗粒的无序程度由空间位置无序和空间方向无序共同决定,空间方向的无序能够加强随机激射的辐射。同时存在两种无序机制的随机介质,在相同条件下它的随机辐射行为要强于仅存在一种无序机制的随机介质。研究结果对于研制新型各向异性随机介质材料具有指导作用。     

用数字光谱法测定透明薄膜折射率

本文所述的方法是F·ABELE'S利用布儒斯特角测定薄膜折射率的推广。     

半导体激光器光束耦合效率研究

在远距离无线光通信中,接收点光功率与光束发散角平方成反比。为了获得小的光束发散角和大的功率耦合效率,必须研究光束准直系统与耦合效率的关系。根据非傍轴远场光分布理论,用光线追迹法对半导体激光器光束准直系统中的功率耦合效率进行研究,给出半导体激光器光束耦合效率的计算方法,并进行计算机模拟。这里的研究结果对半导体激光器光束准直系统设计具有一定的指导作用。     

ABCD Matrix for Reflection and Refraction of Gaussian Beams on the Interface of an Elliptic Paraboloid

Paraboloid form is a commonly used element in optical or quasioptical systems. It is necessary to calculate the reflection and/or refraction of Gaussian beams at the surface of a paraboloid. Based on boundary-value relation in electromagnetic field, the expressions are derived for reflection and refraction of Gaussian beams on the interface of an elliptic paraboloid that divides media of different refractive indices. We extend the analysis to an arbitrary angle of incidence, and convert the obtained results to ABCD ray matrix form. By using these matrices, one can easily design and calculate some actual optical or quasioptical systems, including components with paraboloidal interfaces.     

Measurement of refractive-index profile of optical-fibre preform

An experimental system for nondestructive measurement of the refractive-index profile of an optical fibre preform is reported. The result shows that the profile does not significantly change from the preform stage to fibre stage.     

光纤预制棒制造用精密流体输送系统的设计

光纤预制棒产品的稳定性一直是预制棒生产商关注的焦点。将SiCl4和GeCl4这两种在整个预制棒制造过程中十分关键的原料精确、稳定地输送到沉积炉内参与反应是确保光纤预制棒质量优良的关键。从流体输送的基本概念及控制点详细阐述了用于光纤预制棒生产的精密流体输送系统的设计。     

Index profile measurements of fibers and their evaluation

The refractive index distribution in the core of a multimode optical-fiber waveguide plays an important role in determining the transmission properties of the guide. The closer the index profile is to the required ideal distribution, the greater the resulting information carrying capacity of the fiber. This review paper discusses methods for measuring the refractive index distribution in optical fibers and for predicting their impulse response and signal bandwidth from the measured profiles. Some attention is also given to preform and single-mode fiber profiling.     

Holographic measurement of refractive-index profile of optical fibre preform

A holographic method of measuring the refractive-index profile of an optical fibre preform is presented. It uses the principle of shearing interferometry. The method is simple and allows measurements to be repeated even after the preform has been withdrawn for fibre drawing.     

新型结构之直下式背光模组最佳化设计

在直下式背光模组中,除了均齐度之外,光使用效率在背光模组也是很重要的考虑量,在此将直下式背光模组底部反射板改变构造,在每支灯管之间添加三角形的反射物,使光缘经由三角反射物反射后,其角度与法缘之夹角变小,进而导正光缐的方向.将光缐在三角反射物模组之追跻情形与统计强度分布到优化功能建立于程式中,以缩短模拟时程,同时对均齐度与光使用效率做优化,并与光学软体做比对验证,进而减少棱镜片之成本.在此优化 32 inch 16:9 面板,厚度 2.5cm,灯管数目为 10 支之三角反射物背光模组,加上扩散板后,其最佳出光角度分布之半强角都在 46°,均齐度也有控制在90%以上.根据本研究成果,一些光学膜片可以不置放于此新型背光模组中,将可大幅减少零组件之成本.