共查询到19条相似文献,搜索用时 46 毫秒
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提高声光偏转器空间分辨率的方法研究 总被引:5,自引:1,他引:5
由声光偏转器件(AOD)和四像限探测器(QD)组成的闭环光束跟瞄系统与以往的快速反射镜(FSM)和四像限探测器组成的跟瞄系统相比,具有带宽高、功耗低、重量轻、体积小、重复性好和控制简单可靠等优点。然而,随着控制光束偏转的超声波频率变化的加快,单声光偏转器件(SAOD)的空间分辨点数会随之下降,影响光束控制的精度。提出了一种新型的快速、非机械、高精度光束偏转方法,采用二级声光偏转器件(DAOD)进行光束控制,与一级声光控制器相比具有更快的光束控制速度,更高的空间分辨点数和更宽的扫描范围,可以显著提高光束跟踪的速度和精度。同时还提出了一种求静态和动态分辨点数的方法,并与实验数据进行了比较、分析。 相似文献
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分别在不考虑晶体超声吸收及考虑超声吸收和超声功率角分布的情况下,建立了声光互作用方程。运用空间傅里叶变换方法推导出衍射光场与入射光场在空频域下的传递函数。仿真结果表明,超声吸收使得衍射光光强峰值位置偏离光束中心,光强不再呈高斯分布,会引起卫星光通信发射端的指向偏差。通过研究超声功率和频率与衍射光光强分布的关系发现,超声功率选取某一数值时可以消除峰值位置偏差,将此功率值定义为最优超声功率Popt。求出声光偏转器整个工作频带内的Popt并进行多项式拟合,得到了最优超声功率与超声频率的关系。按照该多项式关系同步调节超声频率与功率可以补偿超声吸收引起的指向偏差。 相似文献
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本文详细报道了红外声光可调谐滤光器的声光偏转效应。分析了产生这一效应的原因进而讨论了它对声光滤光器的影响,最后探讨了它的可能应用。 相似文献
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介绍了应用于频谱分析的高分辨率声光偏转器,描述了偏转器的原理、设计,给出了光波长650nm,带宽50MHz,分辨率20kHz,峰值衍射效率74%(线偏振光)的实验结果。 相似文献
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声光偏转工作模式及其应用研究 总被引:1,自引:0,他引:1
从声光偏转器对光束产生偏转的原理进行了讨论.根据声光偏转器件的工作方式分别归纳和介绍了声光偏转器在各个领域的应用研究.并提出了利用声光偏转器实现时间域信号向空间域转换的新思想. 相似文献
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利用调制传递函数(MTF)分析了声光偏转器的分辨率。建立了高斯光瞳函数与声光偏转器的调制传递函数间的关系。适当选择声光介质与高斯光束(1/e~2振幅附近)的截断比可以增加分辨点数。 相似文献
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WEN Tao ZHUANG Zhao-wen WEI Ji-bo MA Dong-tang 《光电子快报》2006,2(1):34-36
In mobile atmosphere laser communication,the fastand accurate beamsteeringis one of the key techniquesfor acquisition,tracking and pointing(ATP) of laser sig-nals .Compared with the normal loop-locked trackingand pointing system composed of fast steering … 相似文献
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A multicasting photonic space switch reconfigurable in 50 ns is demonstrated utilising commercially available acousto-optic Bragg cells at lambda =0.83 mu m. Insertion loss of 15 dB, extinction ratio of 33 dB, crosstalk of -24 dB and polarisation difference of 0.8 dB are reported.<> 相似文献
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A short double-pass microwave link at 35.8 GHz has been used, with four rapid-response rain gauges, to measure excess attenuation from rain as a function of mean rainfall rate along the path. The results are in good agreement with theoretical predictions. 相似文献
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Approximately 40 h of data from the summer of 1976 were employed in a comparison of radar and radiometer estimates of slant-path attenuation due to rain. McGill Radar Weather Observatory is situated 20 km west of Montreal; the radiometers, separated by 18 km at two sites located about 90 km northwest of the radar, had fixed antennas pointed approximately southeast at an elevation of 18.5 deg. Values of radar reflectivity along the two radiometer paths were used to calculate the slant-path attenuation at 13 GHz as a function of time with a 1 min resolution for direct comparison with the radiometer measurements. It was found that the cumulative distribution of attenuation inferred by radar from each site could be made to agree satisfactorily with the radiometer distribution assuming that rain was present everywhere along the path with a Marshall-Palmer distribution and applying a 1 dB correction to the independently-determined radar calibration. This agreement, close to within a fraction of a decibel, gives confidence to the use of radar records in compiling attenuation statistics. An example is presented of a new application of such records, namely the assessment of rain-induced interference over adjacent earth-space paths. 相似文献
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Douglas Harris 《Journal of Infrared, Millimeter and Terahertz Waves》1995,16(6):1091-1108
The propagation of EM waves through atmospheric fog is reviewed across the spectrum from microwave to optical frequencies. Analytical approaches are considered including Mie computation, and the results compared with published experimental results. Further measurements are called for to clarify discrepancies. 相似文献
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保持良好光束质量的输出对实际光谱合成系统的构建至关重要。从理论上研究光纤激光阵列指向偏差对合成系统光束特性的影响,修正了带有指向偏转角激光队列的入射光场,结合光谱合成的光传输模型和统计学分析,讨论了合成激光光束质量随均匀分布随机扰动的变化规律。仿真结果表明,指向偏差对合成系统的输出特性影响显著,当激光队列的最大偏转角仅为0.05时,合成系统的光束质量就会退化到(6.491.73)。为实现合成光束亮度的定标放大,逐步扩展激光队列的阵列规模,合成系统光束质量的变化会逐渐趋于稳定,以变化稳定时的阵列规模(30路子光束)作为参考,拟合M2因子随最大指向偏转角的变化趋势。 相似文献