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Air-breathing mode laser propulsion experiment with a long-pulse transversely excited(TE) CO2 laser is carried out,and its ignition problem is solved with the ignition needle of lightcraft.Owing to the ignition needle,an order of magnitude reduction in the ignition threshold is demonstrated.The result is compared with previous study.The momentum coupling coefficient is also measured in the experiment and its dependence upon laser pulse energy(6-14 J) and pulse width(20,32,and 40μs) is discussed. 相似文献
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利用分立激光器合成大带宽线性调频步进信号(FSCS)激光信号源以实现高分辨测距。依据FSCS信号测距原理,数值计算了激光器各参数对合成FSCS信号的影响及其误差容限。计算表明,在各激光器参数误差中,起始频率和起始时间误差是引起合成FSCS信号测距分辨力恶化的最主要因素。另外,利用一台中心波长1550nm、线宽为150kHz的线性调波长激光器,通过光学斩波方式,模拟产生了合成FSCS信号,进行了高分辨力的测距演示。理论分析与实验结果表明,采用分立激光器合成高分辨力测距FSCS信号是可行的。 相似文献
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High repetition rate transversely exited atmospheric pressure (TEA) CO2 laser with randomly coded wavelength selection is suggested. The laser wavelength is tuned by a Fabry-Perot (F-P) etalon of low fineness, whose space interval is controlled by a piezoelectric transducer (PZT). A digital controlled programmable voltage source is introduced to vary the voltage applied on PZT so as to swiftly shift the laser output wavelength pulse by pulse. Detailed theoretical analysis is carried out by six-temperature mode rate equations. 相似文献
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Air-breathing mode laser propulsion experiment with a long-pulse transversely excited (TE) CO2 laser is carried out, and its ignition problem is solved with the ignition needle of lightcraft. Owing to the ignition needle, an order of magnitude reduction in the ignition threshold is demonstrated. The result is compared with previous study. The momentum coupling coefficient is also measured in the experiment and its dependence upon laser pulse energy (6 14 J) and pulse width (20, 32, and 40 μs) is discussed. 相似文献
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合成孔径激光雷达(SAL)能实现远距离目标的高分辨成像,但是,其测绘带宽一般很小,不利于其在对地观测中的应用。针对这一问题,给出了宽测绘带SAL实际成像范围的建议,具体研究了采用方位向短、距离向长的非对称光斑照明实现宽测绘带SAL的成像处理问题。采用波动光学衍射理论,给出了这种宽测绘带SAL的详细成像理论描述和数学仿真成像演示。结果表明,由于光学的短波长特性,非对称光斑照明的宽测绘带SAL也近似遵循基本SAL图像形成方法:傅里叶变换实现距离压缩,匹配滤波实现方位图像聚焦。 相似文献
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利用描述CO_2激光器动力学过程的六温度模型理论,建立了计算调Q CO_2激光功率放大器输出特性的数学模型,进行了理论分析和数值计算,并讨论了分光比等参数对输出脉冲特性、输出光谱的影响。结果表明:该调Q CO_2激光功率放大器存在临界增益长度和临界光强分束比,低于临界值时无法获得激光输出;该调Q CO_2激光功率放大器的输出激光脉冲波形、峰值功率、脉冲宽度、输出光谱与光强分束比、抽运电子数密度等参数有关,光强分束比越小,输出的调Q激光脉冲宽度越大,峰值功率越低;该调Q CO_2激光功率放大器利用Q调制的高增益特性,通过控制调Q元件所在的低功率支路可以实现高平均功率的调Q脉冲CO_2激光输出,很好地解决了调Q CO_2激光功率放大器难以高功率运转的问题。 相似文献