论文部分内容阅读
中国科学院国家空间科学中心(空间中心)研制的532 nm多普勒激光雷达主要用于测量临近空间的大气风场、温度和密度等参数。获得单一的、稳定频率的出射激光是该多普勒激光雷达正常运转的关键技术。该激光雷达采用种子注入技术来获得单模的脉冲光,并通过将种子激光锁定在碘分子吸收线的方法来获得稳定的激光频率。调节种子光频率的方法有压电换能晶体(PZT)调节和温度调节两种机制。PZT调节的特点是调节速度快但调节范围窄,而温度调节的响应速度慢但调节范围大。通过协调两种调频机制,并利用比例-积分-微分(PID)控制算法,设计了一套长期稳定的锁频系统。该系统大大降低了对采集卡输出电压范围的要求,并可以使长时间的、大范围的频率漂移由调频较宽的温度调节来响应,而瞬时的频率漂移由响应速度较快的PZT调节来响应,从而保证了系统的长时间运行。该稳频系统的稳频精度可以达到350 k Hz。连续工作时长可达20 h以上。
The 532 nm Doppler lidar developed by the National Center for Space Science (CAS) of the Chinese Academy of Sciences is mainly used to measure atmospheric wind field, temperature and density in the adjacent space. To obtain a single, stable frequency of the outgoing laser is the key technology for the normal operation of the Doppler lidar. The laser radar uses seed injection technology to obtain single-mode pulsed light and obtains a stable laser frequency by locking the seed laser to the absorption line of iodine molecules. The methods of adjusting the seed light frequency are piezoelectric modulation crystal (PZT) regulation and temperature regulation two kinds of mechanisms. PZT adjustment is characterized by fast adjustment but narrow adjustment range, while the temperature control response slow but large adjustment range. By coordinating the two FM mechanisms and using Proportional-Integral-Derivative (PID) control algorithms, a long-term and stable frequency-locked system is designed. The system greatly reduces the capture card output voltage range requirements, and can make a long time, a wide range of frequency drift by FM wide temperature adjustment to respond, and the instantaneous frequency drift by the faster response PZT adjustment Response, thus ensuring the system’s long run. The frequency stability of the frequency stabilization system can reach 350 k Hz. Continuous working hours up to 20 h or more.