Research On Interferogram Acquiring And Control Technology Of Fourier Transform Spectrometer

The Spaceborne interferometer collects the radiation from the atmosphere of the earth. By modulating and interference the infrared radiation is changed into interference signal. Spectrum specification is achieved through Fourier Transform process of the interference signal. Then the atmospheric parameters are derived through metrological calculation. The environment problem is increasingly serious, Global warming, ozone depletion, precipitation acidification become the largest global environment problems affecting human survival and development, space detection spectrometer for global carbon cycle research has been carried out in the world, and the concentration of the greenhouse gases can be obtained accurately through the visible and near infrared spectrum. The indicators ascertainment, project design, key techniques, system realization and performance test result of the high spectral resolution NIR-VIS FTS(Fourier Transform Spectroscopy) are expounded in this paper.A comprehensive research of the development of the NIR-VIS spectroscopy, especially the FTS, in the world is introduced in this paper. The theoretic analysis of the effects on the detective sensitivity of the FTS by every part of the interferogram acquiring system is also introduced in this paper. According to the analysis, technical requirements of the high spectral resolution NIR-VIS FTS interferogram acquiring system are put forward. The key techniques are discussed in detail, including the bias circuit and preamplifiers of the SI photoconductive detector, and the anti-alias filter design.The overall program of moving mirror movement to achieving large physical travel is introduced in this paper. The moving mirror is replaced by cube-corner retroreflector and runs on a rail consisting of line bearing and brushless DC motor.Since the traditional equal optical path difference distance sampling method cannot be used for NIR-VIS wavelengths because of unable to satisfy the Nyquist sampling theorem, a method to calculate the optical path difference distance of each sampling points based on fitting algorithm is developed in this paper.Testing methods and process of the NIR-VIS FTS acquiring system are described in this paper. The test result and the analysis are also given.The research results show that the project of the NIR-VIS FTS electrical system is feasible. The interferogram acquiring system successfully acquires the interferogram of the VIS light and key indicators basically achieve the design requirements. The research results have great reference value to in-depth study of the high spectral resolution, NIR-VIS Fourier Transform Spectroscopy.