基于双光栅单色仪的紫外转动拉曼雷达的模拟计算

The Simulation of UV Rotational Raman Lidar Based on Double Grating Monochromator

转动拉曼测温激光雷达经常用双光栅单色仪来分光,532 nm双光栅单色仪通带较宽,以致白天工作时输出信号混合了较强的天空背景光,无法准确测量白天的大气温度。355 nm双光栅单色仪具有通带较窄、波长短、接收视场角小的特点,减小了背景光干扰,可用于白天温度的测量。紫外双光栅单色仪由光纤、透镜、光栅组成,对它们的参数进行了选择,估算了带外抑制比。对紫外转动拉曼激光雷达系统进行了分析及数值计算,结果表明在激光脉冲能量300 m J,望远镜有效口径356 mm,测量时间20 min的条件下,在晴朗的天气,白天到6.9 km晚上到8.2 km温度测量精度可达到1 K;在有云的天气,白天到3.6 km晚上到4.2 km温度测量精度可达到1 K。

For atmospheric temperature measurement Raman lidar,a double grating monochromator is usually used for isolating the pure rotational Raman spectrum lines. With 532 nm double grating monochromator,there is too much sky background noise in output signal because of its wide filter bandwidth when the rotational Raman lidar works in daytime,so that the lidar can hardly operate effectively. 355 nm double grating monochromator has the virtue of narrow width of passband,short wavelength and small receiving viewing angle,and helps to cut the background light and sounds during the daytime efficiently. The UV DGM consists of optical fibers,focal plates,lenses and gratings.In this paper,the UV double grating monochromator parameters are designed and the rejection ratio of out-band is calculated. For the UV rotational Raman lidar system,we carry out some numerical calculations. The simulated result shows that the system is capable of measuring temperature with the temperature error of less than 1 K up to a height of 6. 9 and 8. 2 km for daytime and nighttime measurements in clear air respectively,and up to a height of 3. 6 and 4. 2 km for daytime and nighttime measurements in cloud air respectively when the laser energy is 300 m J,the telescope diameter is356 mm,and the observation time is 20 min.