外差激光雷达测量水体布里渊散射可行性研究

Potential for Measurement of Water Brillouin Scattering with Heterodyne Lidar

该文分析外差激光雷达测量水体布里渊散射的可行性。借助测量水体布里渊散射的频移 ,可得到水体声速或温度。文中利用两条 12 7I2 吸收线锁定激光输出频率 ,产生稳定的频差约为7.5 GHz发射激光和激光本振。通过对 12 7I2 吸收线稳定度、激光频率稳定度、系统信噪比和反演精度的分析和计算机模拟 ,得出水体深度 2 5 m以内水体布里渊散射频移的测量误差可以控制在2 .5 MHz以内 ,达到水中声速 0 .6 m/ s或温度 0 .1℃的测量精度。

In this paper the potential for measurement of water Brillouin scattering with heterodyne lidar is studied. The water sound speed and temperature can be calculated by measuring Brillouin scattering frequency shift. The required high degree stable frequencies of transmitted and local oscillated lasers are produced by locking two diode pumped lasers at two 127 I 2 absorption lines, respectively. The stability of 127 I 2 absorption lines, stability of laser frequency, lidar system signal to noise ratio and precision of retrieval algorithm are analyzed in detail. The analysis and simulation results show that within 25 meters water depth the precision of water Brillouin scattering frequency shift of less than 2.5MHz can be obtained, which is equal to 0.6m/s for water sound speed or 0.1℃ for water temperature.