Research On The Inter-satellite Differential Lidar Detection Method Of Near Space Temperature And Pressure Profiles In Occultation Mode

The near space is an atmospheric region covering 20 ~ 100 km,which includes the stratosphere,the middle layer and the low heat layer.It is the region of traditional aeronautics and astronautics.The near space is an ideal flight area for civilian field,so the detection of the atmospheric parameters in the near space is of great value.Differential absorption lidar is an active remote sensing technology,which has been widely applied in spaceborne,airborne and ground-based atmosphere detection.It would be promising that the differential absorption lidar can work in the occultation detection mode.Owing to the usage of laser source,the working wavelength of lidar would be agile and an ultra high spectral resolution could be achieved,and the accuracy of retrieval data could be greatly improved.The dissertation focuses on the differential absorption lidar detection method in occultation mode,analyzes the method of temperature and pressure profile detecton in near space and selects the oxygen A band absorption spectrum as the working wavelength.Compared with working in the middle infrared band,the difficulty of the development of the laser source and detector in the near infrared band is reduced.Meanwhile,oxygen is the main gas component in the atmosphere.Compared with the detection via other characteristic gases,oxygen has a more practical application value for the stable ratio of oxygen in the neutral atmosphere,which can improve the detection precision of atmospheric density.In this dissertation,A frequency linear swept differential absorption lidar system is built.We research on the design of AOM driver circuit,the pulse shaping technology of fundamental wave,the power stability of pump wave and second harmonic generation based on PPLN crystal.The optical table experiment is carried out via a 0.5-meter-long multiple passes gas cell,and the measured oxygen transmission spectra are in mostly good agreement with the calculations from HITRAN database.The innovations of this dissertation are listed as follows:(1)The differential absorption lidar in of occultation detection of the atmospheric parameters in near space is discussed.The feasibility of temperature and pressure profile in near space by differential absorption lidar based on occultation mode is studied.A method of frequency linearly scanned differential absorption laser occultation based on oxygen A band absorption spectrum is proposed.(2)A frequency linearly swept differential absorption lidar system is built.The pulse shaping techniques are applied to the nonlinear frequency conversion of 1530 nm laser frequency doubling to 765 nm laser.The efficiency of the frequency doubling is studied by pulse shaping to make the rectangular and gaussian waveforms of the optical fiber amplifier to increase the efficiency of frequency doubling.In the case of gaussian waveform,the highest nonlinear frequency conversion efficiency of 34% is achieved.The differential absorption experiment in optical table is carried out via a 0.5-meterlong multiple passes gas cell filled with oxygen of different pressures,and the measured oxygen spectra are mostly in good agreement with the calculations from HITRAN database.