白天大气测温的转动拉曼激光雷达分光系统

大气测温转动拉曼激光雷达通常采用双光栅单色仪来分离得到拉曼散射信号谱线,然而这种结构存在通带较宽的缺点,以致白天工作时输出信号混合了较强的天空背景干扰,无法准确测量大气温度。Fabry-Perot标准具具有滤波带宽窄、带外抑制比高,以及透射率呈周期性的特点,在光栅单色仪前插入Fabry-Perot标准具,能够有效扣除背景光干扰,同时将氧气的拉曼散射谱线滤除,从而提高了输出拉曼谱线的纯度和输出信号的信噪比,最终可提高温度反演精度并实现日光环境下工作。

Spectroscopic device in rotational Raman lidar for measuring atmospheric temperature in daytime

For atmospheric temperature measurement Raman lidar,a double grating monochromator is usually used for isolating the pure rotational Raman spectrum lines.With such a device,there exists too much sky background noise in output signal because of its wide filter bandwidth when the lidar works in the daytime,so that the lidar can hardly operate effectively.Fabry-Perot interferometer has the virtue of narrow width of passband,high rejection of out-band and periodic transmission ratio.Arranging a Fabry-Perot interferometer in front of the grating monochromator helps to cut out the background light and filter out rotation Raman spectrum lines.That improves the spectral purity of the PRRS portions and heightens the SNR.It enables the lidar to achieve more accurate temperature and realize daytime operation.