【摘要】 设计了一种新颖探测对流层二氧化碳气体的 1572nm 差分吸收雷达,它的发射系统基于脉冲的种子注入 KTP 参量振荡器(OPO)。OPO 由 1064nm Nd:YAG 多模激光泵浦,转换效率 10%,重复频率 20Hz,OPO 的腔长由 PZT 单元和二氧化碳多通道吸收池精确控制,种子注入时,它可以产生单模窄带的信号光脉冲输出, 对应的空闲光输出仍然是多模。窄带 on 光源(线宽小于600MHz)对应于二氧化碳光谱的强吸收线,宽带 off 光源(150GHz)对应于光谱的弱吸收线。on 和off 双波长工作是通过对种子光的 10Hz 开关来得到的。雷达接收系统的核心是近红外光电倍增管和光子计数器,光电倍增管制冷到-60℃以降低其噪声。实验表明,该雷达的信噪比在 6km 以内大于 10 :1(10 分钟 6000 个脉冲累加)。更多还原

【Abstract】 A novel differential absorption lidar (DIAL) with a wavelength of 1572nm for measuring carbon dioxide in troposphere is designed. Its transmitting system is based on an injection-seed KTP Optical Parametric Oscillator (OPO) with a conversion efficiency of 10%. The OPO is pumped by 1064nm Nd:YAG multi-mode laser at repetition rate of 20Hz. The cavity length of the OPO is accurately controlled by a PZT element and a carbon dioxide multi-channel absorption cell. When injecting seed, it will produce single-mode narrow-band light pulsed signal output while the corresponding idler output in multi-mode. The seeded narrow-band light (line width less than 600MHz) corresponds to intense absorption on-line of carbon dioxide spectrum and the unseeded multimode broadband light (150GHz) corresponds to non-absorption off-line. Dual-wavelength operation is achieved by chopping the seed beam for broad-band and narrow-band operation at a repetition rate of 10Hz. The near IR photomultiplier and photon-counter are used in the lidar receiving system. The photomultiplier will be cooled to -60°C for reducing noise. Experiments show that within a range of 6km the signal-noise-ratio of the lidar is more than 10 (6000 pulses accumulating in 10 minutes).更多还原