Sica R J, Sargoytchev S, Argall P S, Borra E F, Girard L, Sparrow C T, Flatt S
Appl Opt. 1995 Oct 20;34(30):6925-36. doi: 10.1364/AO.34.006925.
A lidar system has been built to measure atmospheric-density fluctuations and the temperature in the upper stratosphere, the mesosphere, and the lower thermosphere, measurements that are important for an understanding of climate and weather phenomena. This lidar system, the Purple Crow Lidar, uses two transmitter beams to obtain atmospheric returns resulting from Rayleigh scattering and sodium-resonance fluorescence. The Rayleigh-scatter transmitter is a Nd:YAG laser that generates 600 mJ/pulse at the second-harmonic frequency, with a 20-Hz pulse-repetition rate. The sodium-resonance-fluorescence transmitter is a Nd:YAG-pumped ring dye laser with a sufficiently narrow bandwidth to measure the line shape of the sodium D(2) line. The receiver is a 2.65-m-diameter liquid-mercury mirror. A container holding the mercury is spun at 10 rpm to produce a parabolic surface of high quality and reflectivity. Test results are presented which demonstrate that the mirror behaves like a conventional glass mirror of the same size. With this mirror, the lidar system's performance is within 10% of theoretical expectations. Furthermore, the liquid mirror has proved itself reliable over a wide range of environmental conditions. The use of such a large mirror presented several engineering challenges involving the passage of light through the system and detector linearity, both of which are critical for accurate retrieval of atmospheric temperatures. These issues and their associated uncertainties are documented in detail. It is shown that the Rayleigh-scatter lidar system can reliably and routinely measure atmospheric-density fluctuations and temperatures at high temporal and spatial resolutions.
已构建了一个激光雷达系统，用于测量平流层上部、中层大气和低热层的大气密度波动及温度，这些测量对于理解气候和天气现象至关重要。这个名为“紫鸦激光雷达”的系统使用两束发射光束来获取由瑞利散射和钠共振荧光产生的大气回波。瑞利散射发射源是一台钕钇铝石榴石激光器，它在二次谐波频率下产生600毫焦/脉冲，脉冲重复频率为20赫兹。钠共振荧光发射源是一台由钕钇铝石榴石泵浦的环形染料激光器，其带宽足够窄，能够测量钠D(2)线的线型。接收器是一个直径为2.65米的液态汞镜。装有汞的容器以每分钟10转的速度旋转，以产生高质量和高反射率的抛物面。给出的测试结果表明，该镜子的性能与相同尺寸的传统玻璃镜相似。使用这个镜子，激光雷达系统的性能在理论预期的10%以内。此外，液态镜已证明在广泛的环境条件下都很可靠。使用如此大的镜子带来了几个工程挑战，包括光通过系统以及探测器线性度的问题，这两个问题对于准确反演大气温度都至关重要。这些问题及其相关的不确定性都有详细记录。结果表明，瑞利散射激光雷达系统能够可靠且常规地在高时间和空间分辨率下测量大气密度波动和温度。
