Research On Techniques Of Pulsed Laser State Monitoring And Iodine Absorption Spectrometer In 532nm Doppler Lidar

The 532 nm Doppler lidar developed by Center for Space Science and Research, Chinese Academy of Sciences is mainly used to measure wind field, temperature and density in near space region. Injection seeding technique is employed to obtain narrowband pulsed laser, and iodine absorption spectrometer as high spectral detection device is used to stabilize laser frequency and measure laser Doppler shift. The seeding state of pulsed laser and the spectral stabilization of iodine absorption spectrometer are two factors influenced 532 nm Doppler lidar accuracy. So, the seeding state monitoring of pulsed laser and iodine absorption spectrometer development are main works in this paper.For pulsed laser seeding state monitoring, based on the principle of Q-switch buildup time minimum, designed and developed a pulsed laser seeding state monitor. More details about its hardware and software are introduced in this paper. Its time measurement accuracy is 45 ps,time measurement range is 3.5ns to 2500 ns and pulse repetition ratio is 1KHz. Seeding state monitoring experiments on a Nd:YAG laser were finished, results show that the Q-switch buildup time are 123.27 ns and 134.44 ns for seeding state and unseeding state respectively, the proportion of unseeding state pulse laser is about 8.54% within 1.35 hour. Experiment results indicate that the pulsed laser seeding state monitor has the ability to detect pulsed laser seeding state.For iodine absorption spectrometer, temperature controlling accuracy is the main factor influenced iodine absorption spectra. In order to obtain high stable iodine absorption spectra, designed and developed an iodine absorption spectrometer with better temperature controlling accuracy. Its temperature controlling accuracy is about±0.026℃. Iodine absorption scanning experiment was done, and some spectra under different temperature were obtained. This iodine absorption spectrometer was applied to stabilize the 532 nm laser frequency, the stabilization accuracy is about±150KHz, frequency stability is about 5.32×10-10.