共查询到20条相似文献,搜索用时 78 毫秒
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大气波导对舰载雷达探测距离的影响 总被引:1,自引:0,他引:1
大气波导可使舰载雷达的探测距离增大而实现超视距探测,如果能够准确、可靠地预报大气波导条件下雷达发现目标的最大距离,在军事上将具有重要意义。本文论述了形成大气波导的气象条件和雷达条件,给出了受大气环境影响的雷达探测距离的计算公式,提出了在实际应用中对大气波导的测量和雷达探测距离的预测方法。 相似文献
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获取多波长气溶胶光学特性的方法研究 总被引:1,自引:0,他引:1
为了获得多波长气溶胶的垂直消光特性,本文提出了一种综合利用光学粒子计数器、能见度仪和激光雷达获取多波长气溶胶光学特性的新方法。该方法根据光学粒子计数器测量的谱分布、能见度仪测量的能见度和激光雷达测量的消光后向散射比反演出气溶胶粒子(λ=0.532μm)的折射率,作为初始值,根据气溶胶模式提供的折射率随波长的变化关系,确定其他波长上的折射率。再根据气溶胶折射率和谱分布计算不同波长上的消光特性,最后采用激光雷达测量的垂直消光廓线来反演其他波长上的消光廓线。以0.532μm,1.06μm和 10.6μm三波长为例,给出北京2004年8月24日气溶胶在不同波长上的垂直消光廓线。 相似文献
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测量臭氧在大气中垂直分布的最有前途的方法之一是最近在紫外光谱区用差分吸收法的雷达探测.这种雷达的工作原理在于:记录在大气中散射的两个接近波长的光信号,其中之一在所研究的气体中强吸收,第二个波长是参考波.关于在紫外光谱区的雷达系统用于测量对流层和平流层臭氧的浓度已有一些报导. 相似文献
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《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1976,64(7):1059-1092
A review of the status of research towards achieving lasing action in the vacuum ultraviolet and soft X-ray spectral regions is presented. An analysis of the general problems likely to be encountered is accompanied by numerical results for those approaches currently considered promising. Progress on each approach is detailed and various possible methods of verifying the presence of gain with their relative merits are discussed. Research areas requiring Application of short-wavelength lasers also are given. 相似文献
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本文用两种波长不同的激光——Ar~+激光和CO_2激光,对以石英为衬底的a-Si SOI进行了激光结晶。两者的结晶机理不同,得到了不同的结晶形貌。 相似文献
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Chang-Hasnain C.J. Maeda M.W. Harbison J.P. Florez L.T. Lin C. 《Lightwave Technology, Journal of》1991,9(12):1665-1673
A two-dimensional (2-D) surface emitting laser array emitting 140 unique, nonredundant, uniformly separated, single-mode wavelengths in the 980-nm regime is described. The wavelength separation between neighboring lasers is as small as 0.3 nm. A large total wavelength span of 43 nm was obtained without compromising the performance of the lasers. All 140 lasers have nearly the same threshold currents, voltages, and resistances. The techniques used are generic and can be readily extended to both longer and shorter wavelength lasers. The authors also report the first wavelength division multiplexing system experiment using part of this laser array. A BER (bit-error ratio) of 10 -9 at 155 Mb/s was obtained with simultaneous operation of four lasers at a wavelength separation of 1.5 nm. Negligible optical and electrical crosstalk was observed between the lasers 相似文献
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Hong-Yuan Shen Zeng R.R. Yu-Ping Zhou Yu G.F. Cheng-Hui Huang Zheng-Dong Zeng Zhang W.J. Ye Q.J. 《Quantum Electronics, IEEE Journal of》1991,27(10):2315-2318
The oscillation condition of a simultaneous multiple wavelength laser has been established and used to analyze the possibility of simultaneous oscillation in various neodymium host crystals, such as Nd:YAG, Nd:YLF, Nd:BEL, and Nd:YAP crystals at the transitions from 4F 3/2-4I 13/2 and 4F 3/2-4I 11/2. It is shown that this kind of laser can be realized in all the described crystals in a pulsed state. In general, continuous wave (CW) operation, however, can only be achieved for Nd:YAP. On the basis of these results, CW simultaneous double wavelength lasing has been achieved in a Nd:YAP crystal for the first time at both 1.0795 μm and 1.314 μm 相似文献
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In this paper, the influence of laser wavelength instability, polarization fading and phase fluctuation on local heterodyne detection wavelength scanning Brillouin optical time domain reflectometer (WS-BOTDR) is theoretically analyzed, and a local heterodyne detection WS-BOTDR system is built for experimental verification. The experimental results show that with the increase of sensing distance, the adverse effect of laser wavelength instability, polarization fading and phase fluctuation on local heterodyne detection WS-BOTDR is gradually aggravated, which will lead to the broadening and distortion of the wavelength power spectrum (WPS), resulting in large errors in demodulated Brillouin central wavelength (BCW) and temperature. The average temperature measurement errors at the positions of 1 km, 5 km, 9 km non-heating section and 9.45 km heating section are 1.76 °C, 3.42 °C, 3.89° C and 4.3 °C, respectively. 相似文献
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由于太赫兹波电光取样探测技术中电光晶体存在的色散关系, 探测光的波长会直接影响到电光取样的探测带宽和效率.由于该色散关系的存在, 不同的电光晶体在电光取样中响应函数不同.本文研究了两种典型的电光晶体-碲化锌和磷化镓晶体的响应函数, 发现在选取的四种探测激光波长内(600 nm、800 nm、1200 nm、1600 nm), 800 nm的探测激光更合适碲化锌晶体, 1200 nm的激光更合适磷化镓晶体.对于不同厚度的晶体, 存在一个最优化的探测激光波长, 使得该晶体的电光响应函数有最宽的带宽. 相似文献