共查询到19条相似文献,搜索用时 140 毫秒
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光电装备的光学窗口对入射激光有较强的反射特性,即猫眼效应现象。为了研究利用猫眼效应来进行主动探测的适用条件,弄清探测激光入射角对猫眼效应反射特性的影响,建立了斜入射猫眼效应反射模型,分析并仿真了探测激光在目标系统处的入射角不同的情况下的后向反射激光特性,以及探测系统所能够接收的原路返回激光的远场能量分布情况。结果表明:对于特定的目标系统,猫眼效应现象只存在于一定的探测激光入射角范围之内,在此范围之内,猫眼效应反射特性与探测激光的入射角关系密切;基于猫眼效应的激光主动探测、定位等应用也是可行的。 相似文献
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“猫眼”效应在激光主动侦察等领域具有广泛的应用,猫眼回波的功率分布是一项关键技术指标。激光束通过光阑会发生受限衍射,以Collins公式为基础,推导了猫眼回波光场的分布函数,数值计算了探测面上的光场分布,研究了“猫眼”系统中透镜口径、焦距以及探测距离、激光束束腰、离焦量等对猫眼回波功率分布的影响。并基于CCD搭建实验系统对猫眼回波功率分布以及衍射图样进行观测。观测结果表明:回波光场携带明显的衍射信息;探测器偏离成像透镜焦平面时,有限探测距离内猫眼回波光斑的峰值功率随着探测距离的增大而先增大后减小,最大值出现在约100 cm处。观测结果与理论数值计算吻合很好,验证了光阑衍射效应对回波功率的分布造成了明显的影响;研究结果对猫眼主动探测系统的研制具有很好的指导意义。 相似文献
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本文研究了大气湍流和探测光空间相干性对倾斜离轴激光束通过猫眼光学 镜头反射光光强特性的影响. 研究表明: 由于光阑效应以及光束倾斜或离轴, 反射光光强出现振荡和非对称分布现象. 大气湍流不会改变其非对称性, 但湍流中其光强不再振荡. 当猫眼光学镜头存在微弱正离焦δmax情况下, 轴上光强可达到最大值. 猫眼光学镜头焦距越大, 所需δmax越大. 但是, 大气湍流和探测光相干性好坏都不会改变所需δmax值. 在大气湍流中传输距离足够远时, 反射光强会成为离轴类高斯分布. 随着传输距离的增大, 相干性越差的探测光的反射光束扩展可以更小, 这与部分相干光自由空间传输规律完全不同. 探测光相干性越好, 其反射光强受湍流的影响越大, 但差异不大. 本文所得结果对激光主动探测的应用具有意义.
关键词:
猫眼光学镜头
大气湍流
部分相干光
光强 相似文献
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运用矩阵光学理论以及将硬边光阑窗口函数展开为有限个复高斯函数之和的方法, 对激光束辐照猫眼光学镜头时产生的猫眼效应机理进行了理论推导. 通过数值计算对猫眼效应的反射规律进行了分析, 并利用532nm激光辐照一个变焦范围为12—72mm的光学镜头进行了猫眼效应的实验验证, 从而得出了猫眼效应反射光特性与入射激光参数以及猫眼光学镜头的口径、焦距、离焦量等基本参数之间的关系. 研究表明, 猫眼效应反射光特性与猫眼光学镜头参数和入射激光参数密切相关, 且当猫眼光学镜头位于近场和远场的情况有很大不同. 根据入射光束
关键词:
猫眼光学镜头
猫眼效应
高斯光束
反射特性 相似文献
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扩束准直光学系统中光学元件失调对高斯光束传输变换的影响分析 总被引:2,自引:1,他引:1
基于广义惠更斯-菲涅尔衍射积分公式, 以高斯光束为激光束模型,推导了激光光束通过失调扩束准直光学系统的传输公式,分析了光学元件失调对扩束准直光学系统输出光束传输特性的影响,并在此基础上进行了仿真。实验结果表明,高斯光束通过失调扩束准直光学系统时,出射光束变为偏心高斯光束,光学元件失调程度越大,输出光束越偏离光轴,光束质量越差。在同样的失调下,长焦距光学元件对输出光束影响更大,因此在激光扩束准直光学系统中,调整长焦距光学元件更为重要。 相似文献
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Detection and jamming experiment of optical surveillance device in night equipment transportation北大核心CSCD 下载免费PDF全文
针对装备运输过程中可能遭遇侦拍的风险,结合运输安全需求,分析市面上常见的4类消费级侦拍装置(手机、卡片数码相机、单反相机和数码摄像机)的光电可探测性,并实现对各装置的有效干扰。通过搭建“猫眼”激光探测、激光干扰及回波信号接收系统,重点突破典型小口径侦拍装置的探测与识别,以及“猫眼”探测端与目标端的双向成像等理论和关键技术。在此基础上分析不同距离、干扰波长和孔径情况下可见光波段激光对“猫眼”目标的探测及成像干扰效果,并提出一种图像干扰效果评价标准及不同光学侦拍装置的有效干扰阈值。实验结果表明:典型光学侦拍装置在实验距离内具有良好的光电可探测性,并且可被有效干扰;在激光束完全覆盖镜头通光孔径时,目标与装置距离越近,激光束散角越小,波段越接近人眼敏感程度最大波段(555 nm),激光光束产生的非伤害性成像干扰效果越好。 相似文献
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This paper reports on the applicability and the limitations of reticles as standards in laser diffraction spectroscopy. In comparison with standard materials, reticles carry some advantages with respect to their ease of handling. In contrast, the static features on a reticle cannot faultlessly simulate a real measurement on a moving particle system. The difference becomes visible in the form of speckles superimposed on the diffraction pattern and is dependent on the positions of the features on the reticle. As long as the feature positions are random, the speckles are also randomly distributed over the pattern and the measurement data averaging the intensities over the detector ring areas are only slightly disturbed. However, reticles containing only non-overlapping features contravene the requirement of complete feature position randomness and their diffraction patterns show a dark ring close to the center. The normal evaluation of these diffraction patterns delivers size distributions which are too narrow and shifted to smaller particle sizes. Nevertheless, by defining a reticle specific phase function and by implementing it in the evaluation algorithm, the correct particle size distribution is obtained. Simulations have been performed to investigate reticles with and without overlapping features. 相似文献
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Summary The theory of the optical, electro-optical and elastic properties of liquid-crystal blue phases is presented. The efficiency
of the optical methods of study of blue phase is underlined. The effects of the many-wave diffraction optics in blue phases
are discussed in detail. The universal temperature dependence of the blue-phase order parameter is found for the experimentally
observed blue phases.
Work presented the First USSR-Italy Bilateral Meeting on Liquid Crystals held in Portonovo, Ancona (Italy), September 30–October
2, 1987. 相似文献
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Liquid crystals are anisotropic materials whose optical properties can be easily controlled applying an electric field. For this reason, they are widely used in electro-optical devices. Besides other applications, liquid crystals electro-optical devices are suitable for laser beam manipulation. In this paper, we present some devices developed or studied in our laboratory: a twisted nematic liquid crystal (TN-LC) polarization rotator, a TN-LC protected light sensor, a polymer dispersed liquid crystal (PDLC) light modulator, a PDLC optoelectronic polarizer and a polymer liquid crystal (PoLiCryst) light modulator. 相似文献
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Based on the definition of first order moment and the approximate three-dimensional analytical formula for oblique laser beam passing through a cat-eye optical lens with center shelter and inclined detector, the analytical expression of centroid position of the cat-eye effect reflected light under far-field condition has been deduced. Variable laws of centroid position deviation at the return place are performed by numerical calculation, and analyzed physically. The results show that the centroid position deviation is directly caused by the oblique incidence of the detected laser, and the focal shift of cat-eye optical lens plays a more important role in the increase of the centroid position deviation. 相似文献
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Based on diffraction optical theory, diffraction of a laser beam with periodic amplitude modulation and phase distortion is derived in 3ω optics system. Influence of defocus distance and focal length of a focusing lens on intensity distribution of diffraction light is investigated by numerical simulation. The results show that appropriate distance away from the focus spot and increase the focal length in final optical systems are beneficial to control the modulation of light intensity fluctuations and reduce the optical components damage caused by small-scale self-focusing effect. 相似文献