Research On Hyper-spectral Information Acquisition Techniques

As we all known, CO₂ and CH₄ in the atmospheric increased year by year, and the climate change caused by these greenhouse gases has become increasingly apparent. But for the gases’ origin, distribution and convergence, people still lack of awareness. So it is indespensible to obtain regional global carbon source and sink, by detect the CO₂ concentration distribution in the atmosphere. This thesis is around the atmospheric CO₂ column concentration monitoring to carry out the hyper-spectral information acquisition technology research and related system design.This thesis first introduces the research background and significance, states the status qua of greenhouse gases detection at domestic and overseas, illustrates the necessity and urgency of research work. Then based on the basic principles of the spacebrone atmosphere remote sensing detection, describes the overall process of atmospheric detection in more detail, including the interaction of the radiation and the atmosphere, the different kinds of hyper-spectral remote sensing instrument accessing the radiation information, and the inversion algorithm, puts forward a method of high spectral resolution instrument. Next, processing from the demand of high precision atmospheric CO₂ concentration detection, analysis and discuss the influence and feasibility of spectrometer’s various indexes on the measurement, including spectrum channels, resolution, spectral sample rate, SNR of the instrument, F-number and the detector, come forward the specifications of the whole system. Afterwards, develop the hyper-spectral CO₂ detecting instrument design, mainly complete the optical design in 0.765μm, 1.606μm and 2.06μm waveband,the specrum resolution of each band can reach 0.044 nm, 0.08 nm and 0.1nm, by image evaluating and analysing, the result can meet the system requirements. Specific to the 1.606μm wave band, design and set up the principle verified platform, including the stray light and tolerance analysis, electronics system design and implementation, and PC programs. After finishing the spectrometer, a series of experiments is in process, including test the noise and SNR of the spectrometer. Then discuss the current calibration method of high spectral resolution instrument, put forward a spectral calibration scheme, acquire the spectra, and analyse the experimental data on the spectral calibration. Finally, aiming at the future development, develop a wide swath detection system, complete the optical design and image evaluation, the system can achieve hyper-spectral detection in 200 km swath width and 3x3 km2 space resolution. At the end of the thesis carried out the comprehensive summary and generalization, proposed some problems existing, and the future work of accurate monitoring of the atmospheric CO₂ column concentration is prospected.The major innovations of this paper:（1）Aim at the system’s high resolution requirement, analysis of the effect of each index and expound the necessity. On the strength of the study, paper proposes an optical system design scheme based on plane reflection grating, three-channel can realize 0.044, 0.08, 0.1 nm spectral resolution respectively. Setup the 1.61 μm channel prototype system;（2） Use the In Ga As detector developed and produced in China in the hyper-spectrum detection field for the first time, and solve the problem of fine absorption spectrum and the focal plane coupling;（3） Based on the original scheme, direct at the wide detection application requirements of greenhouse gases, breakthrough the existing high spectral resolution technology, put forward a wide detection scheme by using immersion diffraction grating. The scheme can realize greenhouse gas detection in 200 km ground swath and 0.1 nm spectral resolution.In recent years, the spacebrone high precision CO₂ concentration monitoring technology has gradually become an emphases attention problem around the world, and scientists also regard it as a research hot spot. However, in our country, many key components involved in in the instrument and high spectral resolution detection research are still in the initial stage. Therefore, the research work of this thesis contributes to promote the study of our country in the field of spacebrone hyper-spectral CO₂ concentration monitoring and related technologies. It has the certain exploration and innovation, and laid the foundatio n for the future research in global regional carbon “source” and “sink”.