直接探测激光测风雷达发射激光线宽对探测的影响
Effect of transmitted laser linewidth on wind measurement of direct detection lidar using double-edge technique
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摘要: 论述了Rayleigh散射双边缘直接探测激光测风雷达发射激光线宽对探测灵敏度和误差的影响。使用Monte-Carlo方法模拟了大气后向散射回波半高宽(FWHM)和发射激光线宽的定量数值关系。把这个关系拟合为一个二次多项式，计算了由发射线宽引起的测量灵敏度和误差。对于探测波长是355 nm的情况，当发射线宽从单频增加到2 GHz时，后向散射回波线宽从3.853 GHz非线性地增加到5.371 GHz。发射激光线宽的加宽对探测影响很大，当发射线宽从单频增加到2 GHz时，测量灵敏度从0.003 1降低到0.001 9，测量误差从0.323 m/s增大到0.518 m/s,计算中假定探测信噪比和累计激光脉冲数都是1 000。
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关键词:
- 测风雷达 /
- Rayleigh散射 /
- 双边缘技术 /
- 线宽
Abstract: The effect of linewidth of the transmitted laser on measurement sensitivity and error of double-edge noncoherent wind lidar is presented. The quantitative relationship between linewidth of the transmitted laser and the FWHM(full width at half maximum) of the backscattered spectrum was simulated by using the Monte-Carlo method since it cannot be expressed by an analytic formula. The relationship was fitted by using quadratic fit and was used to calculate the measurement sensitivity and error furthermore. The FWHM of the backscattered spectrum increases from 3.853 GHz to 5.371 GHz while the linewidth of the transmitted laser increases from monochromatic to 2 GHz. The measurement greatly suffered from the broadening of the linewidth of the transmitted laser. The measurement sensitivity reduce-
Key words:
- wind lidar /
- rayleigh scattering /
- double-edge technique /
- linewidth
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