共查询到19条相似文献,搜索用时 468 毫秒
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基于模拟退火算法的偏振控制器波片相移特性研究 总被引:8,自引:3,他引:5
按晶体波片的快轴与水平方向成0°、45°、0°、45°顺序排列构造四波片偏振控制器。固定各波片的快慢轴,利用模拟退火算法进行反馈控制,通过改变各波片的相位得到所需的偏振态。仿真结果说明,利用模拟退火算法进行负反馈控制,其收敛速度较快,收敛后光强波动小于2%;该控制器能在各波片相移范围限制在0~2π情况下实现偏振态的无端控制。为消除可能出现的复位死角,在模拟退火算法基础上加入强制无端复位方法,复位过程稳定。控制过程中该控制器各波片的相移步长可变,但寻优过程中最大步长不超过3.36°,强制复位过程中最大步长不超过18°,因此控制电压的变化平缓。 相似文献
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旋转波片Stokes偏振仪是最常用的测量光束偏振态的仪器。波片快轴方位误差是影响旋转波片Stokes偏振仪的主要误差源之一。为了研究波片方位偏差对测量精度的影响,提出了一种描述波片快轴方位误差向最终的偏振测量误差传递的数学模型,并引入协方差矩阵法表征偏振测量误差。根据这一模型,获得最优的偏振仪配置参数。在推导过程中,假设波片方位误差服从同一高斯分布。基于此误差模型,得到如下结论:(1)由波片方位误差引入的测量误差与光强测量次数N成反比;(2)测量误差独立于入射光强度,但是依赖于入射光偏振态(s1, s2, s3)和波片的位相延迟量δ;(3)波片位相延迟量在(103.22°, 116.13°)范围内时波片方位误差引入的测量误差最小。最后,经过仿真实验证明,所得解析结果与仿真模拟结果相一致。 相似文献
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四区域法消除偏振棱镜缺陷对波片相位延迟测量的影响 总被引:1,自引:0,他引:1
在起偏器-待测波片-检偏器系统基础卜提出一种四区域测量波片相位延迟量的方法.调整待测波片和检偏器的方位角,获得相应的四组光强值,通过线性运算得到待测波片的相位延迟量,完全消除了起偏器和检偏器不完全消光带来的误差.由于测量系统中不存在标准波片或其他相位调制元件,允许测量波长仅受偏振棱镜和探测器的限制,因此四区域法可适用于很大波长范围内的波片测量.以λ/4波片为例,理论分析了测量系统利用四区域测量法后的仪器误差为σφ≤士3.49065×10-3rad(约0.2°),精度比原算法提高约1个数量级.实验验证了四区域法能有效提高系统精度. 相似文献
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分振幅型全Stokes同时偏振成像仪具有实时性好、空间分辨率高、精度高等优点,有很高的应用价值.分振幅型全Stokes同时偏振成像系统利用偏振分束器、1/2波片和1/4波片将入射光Stokes矢量调制在4幅图像中,可解析入射光Stokes矢量. 1/2波片和1/4波片的相位延迟误差对Stokes矢量测量精度有着不可忽略的影响.建立了包含上述两种误差的Stokes矢量测量误差方程,分析了1/2波片和1/4波片相位延迟耦合误差对自然光、0°/45°线偏光、左旋圆偏光等典型基态入射光的Stokes矢量测量误差的影响,推导了任意偏振态的Stokes矢量测量误差的表征方法.在邦加球球面和球内选取不同偏振度的Stokes矢量作为入射光进行仿真.结果表明, Stokes矢量测量误差和偏振度测量误差均随着入射光偏振度的增大而增大.选取入射光偏振度为1时的偏振测量精度评估系统.为满足2%的偏振测量精度, 1/2波片相位延迟误差应在±1.6°内, 1/4波片相位延迟误差应在±0.5°内.这对提高系统的偏振测量精度具有重要意义,为系统设计和研制提供了重要的理论指导. 相似文献
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模拟退火算法在无端偏振控制器中的应用 总被引:1,自引:1,他引:0
构造了由四个相移范围在0~2π的电光晶体波片组成的偏振控制器,利用模拟退火法作为其反馈控制算法.仿真计算表明,该偏振控制器是无端的,在较优的控制参量下,其输出的偏振态是稳定的,光强波动小于1%.对于四波片偏振控制器,模拟退火算法的控制参量研究表明,为得到较佳的控制效果,可把内外循环次数各限制为3次,以减少处理器时间;其初温T0应取在0.1附近;温度更改常数p宜取在0.2左右;状态产生常数s对输出的稳定性影响最大,仿真说明设在 0.005~0.01间为好. 相似文献
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三波片偏振态变换器误差分析 总被引:1,自引:0,他引:1
在相干光通信和高速光纤通信等领域,要求偏振变换器具有高的偏振变换精度。对由两个可独立旋转的λ/4波片和一个可独立旋转的λ/2皮片组成的三波片偏振变换器的偏振变换误差进行了详细的分析。利用二维几何方法推导出了由波片方位角误差造成的偏振变换误差模型,并进行了数值计算。研究结果表明,三波片不同的组合方式对偏振态的变换精度有影响。其中,λ/4 λ/2 λ/4组合具有最高的偏振变换精度,λ/2 λ/4 λ/4次之,λ/4 λ/4 λ/2的最差;经三种偏振变换器变换后偏振态的方位角的变换误差较大,变换后偏振态的椭率角的误差很小;三种偏振变换器都可以实现较高精度的任意偏振态变换。 相似文献
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消色差/4波片具有一定的二向色性和相位延迟量误差,导致仪器偏振测量产生误差。从考虑全偏振CCD相机自身偏振效应的辐射模型入手,借助积分球辐射源和高精度辅助旋转偏振器,研究系统级非理想消色差/4波片的标定方法。结果发现:消色差/4波片的二向色性和相位延迟量参数随仪器的工作波长与带宽发生变化,波段650 nm(相位延迟量88.90)和750 nm(相位延迟量88.65)消色差效果相对较好,而波片在波段850 nm(相位延迟量84.33)相位量偏差较大;通过相位延迟量的标准误差分析,得出消色差/4波片的系统级标定方法精度优于0.8。 相似文献
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在地平式折轴望远镜中开展自适应光学激光导星实验,研究了共孔径发射接收信标激光束偏振耦合分光效率随望远镜方位角和天顶角变化的补偿技术。提出了一种由四分之一波片和法拉第旋光器构成的相位补偿器,通过旋转四分之一波片以实时补偿由于望远镜旋转导致的光路相位延迟量的变化。数值计算表明,望远镜处于任意方位角和天顶角位置时,通过1°步长旋转四分之一波片,可使补偿后的偏振分光效率理论上达到99.90%以上。实验从原理上定性地验证了该方法的有效性。只要测量出镜面的相位延迟,便可计算得到望远镜处于不同方位角和天顶角情况下有效补偿所需的四分之一波片旋转角度,据此可建立实用的旋转波片偏振补偿装置。 相似文献
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We demonstrate an in-line polarization controller based on a hollow optical fiber filled with a nematic liquid crystal by fabricating thin-film electrodes on the cladding of a fiber. The polarization controller consists of three control sections with fixed optic axes, which operate as phase retarders. The phase retardation in each section is controlled by the magnitude of the applied electric field. The full wave retardation voltage of the polarization controller is approximately 85 V. 相似文献
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An X-ray double phase retarder system composed of two transmission-type phase retarders is proposed and developed in order to compensate for off-axis aberration (phase-shift inhomogeneity due to angular divergence of incident X-rays). The scattering planes of the two phase retarders are set to be inclined by 45 degrees with respect to the plane of incident polarization, but the two phase retarders give Bragg reflections in opposite directions. By using this X-ray optical system, vertically polarized X-rays with a 0.99 degree of linear polarization were obtained from horizontally polarized synchrotron radiation with a horizontal beam divergence of 20 arcsec (0.1 mrad). This value is favorably compared with the value of 0.87 which was obtained using a conventional single phase retarder of identical total thickness, 627 microns. The comparison was made at the nickel K-absorption edge (8333 eV) with the condition that 47% of incident X-rays were transmitted through the two phase retarder crystals. The crystals were (100)-oriented diamond plates giving asymmetric 111 Laue reflections. 相似文献
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Half-wave retarders are primarily used in rotating the plane of polarization of polarized light. These retarders usually exhibit strong wavelength dependence. In this paper, the design and characteristics of an achromatic half-wave plate, formed by a cascaded system of birefringent plates, have been studied. Pancharatnam proposed a combination of three retarders in series and discussed the possibility of fabricating reasonably good achromatic quarter-wave plate with a suitable combination of their retardance. The system studied here is similar in construction to Pancharatnam configuration and behaves as an achromatic half-wave plate over a wide spectral range. The proposed configuration exhibits a maximum variation of only about ±1.4 degree over the entire wavelength range of 500–750 nm. In our analysis we have used Jones matrix formalism for the derivation of the general expression for the equivalent retardation and the azimuth of the combination. 相似文献
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综合等效介质理论和表面等离子激元(SPP)Bloch模型,对比分析了两种新的亚波长光栅结构:二维矩形金属光栅和二维椭圆柱金属光栅。利用时域有限差分(FDTD)算法,对比分析了两种结构的透射率及其相位延迟与入射光波长及偏振角变化的关系,尤其两种结构实现λ/4波片功能所对应的透射特性。仿真结果表明,当入射光偏振角为75°时,两种结构均可实现λ/4波片功能,此时二维矩形和椭圆柱金属光栅的透射率分别为0.77和0.67,表明二维矩形金属光栅比椭圆柱光栅具有更好的透射效果。对应550~800nm的入射波长,两种光栅在各自允许的入射偏振角范围内均表现了较为平坦的宽带透射特性。 相似文献
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A novel method to stabilize a channeled spectropolarimeter is described. The fluctuating retardations of the high-order retarders used in the spectropolarimeter are calibrated in parallel to the measurement of the wavenumber-dependent state of polarization (SOP) of light. Both the calibration of the retarders and the measurement of the SOP can be made simultaneously using a single light to be measured, and hence the resultant wavenumber-dependent SOP is almost immune to fluctuation of the retardations. The effectiveness of this method is experimentally demonstrated with retardation fluctuations induced by a temperature change up to 40 degrees C. 相似文献
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Distributed Measurement of Birefringence by P-OTDR Assisted with Piezoelectric Polarization Controller 下载免费PDF全文
We propose a new polarization sensitive optical time domain reflectometry (P-OTDR) setup assisted with a piezoelectric polarization controller (PPC). The input state of polarization can be changed by varying the voltage of PPC without any rotatable instrument, and only one optical receiver is used to detect the backward beam. We measure a single mode fibre and get the distribution of birefringence along the SMF. 相似文献
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Tharp JS Lopez-Alonso JM Ginn JC Middleton CF Lail BA Munk BA Boreman GD 《Optics letters》2006,31(18):2687-2689
Meanderline wave plates are in common use at radio frequencies as polarization retarders. We present initial results of a gold meanderline structure on a silicon substrate that functions at a wavelength of 10.6 microm in the IR. The measured results show a distinct change in the polarization state of the incident beam after passing through the device, inducing a 74 degrees phase retardance between horizontal and vertical components. A high degree of polarization (88%) is maintained in the transmitted beam with an overall power transmittance of 38% and a beam profile that remains essentially unchanged. 相似文献
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Terahertz achromatic quarter-wave plate 总被引:3,自引:0,他引:3
Phase retarders usually present a strong frequency dependence. We discuss the design and characterization of a terahertz achromatic quarter-wave plate. This wave plate is made from six birefringent quartz plates precisely designed and stacked together. Phase retardation has been measured over the whole terahertz range by terahertz polarimetry. This achromatic wave plate demonstrates a huge frequency bandwidth (upsilonmax/upsilonmin approximately 7), and therefore can be applied to terahertz time domain spectroscopy and polarimetry. 相似文献
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A tunable comb filter using single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop 下载免费PDF全文
A novel tunable comb filter composed of a single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop is proposed and experimentally demonstrated. The filter tunability is achieved by rotating the polarization controller. The spectral shift is dependent on rotation direction and the position of the polarization controller. In addition, the adjustable range achieved by rotating the half-wave-plate polarization controller is twice higher than that of the quarter-wave-plate one. 相似文献