The Study On Tomography Observation Technique For OH Radicals Detection In The Upper Atmosphere

There is a very small amount of OH radicals in the middle and upper atmospheres,and its content and vertical spatial distribution will affect the destructive effect of the ozone layer and the hemispheric climate asymmetry.We usually achieve effective detection of atmospheric components through hyperspectral techniques,and higher spectral resolution can increase detection sensitivity.Spatial heterodyne spectroscopy can obtain extremely high spectral resolution within a relatively narrow spectral range.Combined with tomographic inversion techniques,dual-channel limb observation methods with orthogonal fields of view can also be used to obtain three-dimensional spatial distribution information of detection objects.The spatial heterodyne differential field-of-view imaging spectrometer uses a novel hyperspectral spectroscopic scheme of spatial interference type.It uses the area array detector to collect all interference data points at the same time,which can effectively reduce the noise and obtain the imaging spectrum.The spectral recovery of the interferometer is using Fourier transform to transform the interferometric data collected by the instrument from the time domain to the frequency domain,depending on the spectral response of each pixel in the detector and the calibration parameters at the device level.At the same time,the configuration relationship between the focal plane device and the interferometer will also affect the authenticity of the final acquired spectral information.In order to ensure the effective observation of the three-dimensional spatial distribution of OH radicals by the satellite platform,the technical features of the instrument scheme and the on-orbit work mode are considered for the targeted design of the optical and electronic systems.After quantifying and analyzing the key technical parameters of the OH radical detecting instrument in the middle and upper atmosphere,this paper presents the design and analysis of the optical system,mechanical structure and the electronics system.Then,the related characteristics analysis and performance optimization of the detector are studied.The specific work of the thesis includes the following aspects:1.Firstly,the spatial heterodyne simultaneous subfield imaging technology was studied.The orthogonal observation technical scheme was discussed.Then the key technical parameters of the detecting instument were quantitatively studied and analyzed,and the application indicators and key technical parameters of the detecting instrument were defined.Ultimately gave the corresponding optical system design,mechanical stucture design and electronic system design.2.The influence of detector dark current on the signal-to-noise ratio and dynamic range of the spatial heterodyne spectrometer was studied.The experimental study on the effects of detector temperature on the instrument's SNR was carried out.After comprehensive consideration of the power consumption and signal-to-noise ratio of the instrument,the optimum operating temperature of the detector was choesed.3.The research on the alignment error analysis of the detector and the method of the field-of-view registration of the detector dual-channel spectrometer are studied.Theoretical models for analyzing the alignment errors which are divided into three kinds are presented in this paper.Based on these models,the tolerance of these errors has been given,respectively.The result of simulation experiments shows that when the angle of slope error,tilt error,and rotation error are less than 1.21°,1.21 °,0.0660 respectively,the alignment reaches an accpetable level.4.The influence of the detector response parameters on the spectral recovery of the spatial heterodyne spectrometer was studied.For these parameters,the detector screening experimental device and the screening method were designed.A probe screening experiment was carried out,and the detector with the best overall performance was selected from the alternative detectors.5.For the two-channel spatial heterodyne spectrometer in orthogonal mode,the performance parameters such as field of view,spectral resolution,signal-to-noise ratio and other important parameters are evaluated.The test methods and test results are given.Based on this,an aerial flight experiment was carried out.The experimental results show that the instrument can be applied to the detection of OH radicals in the middle and upper atmospheres.