Key Performance Simulation and Analysis of Space Borne Fourier Transform Infrared Spectrometer

With the advantages of high spectral resolution, wide spectral coverage and large throughput, space borne Fourier transform infrared spectrometer (FTS) plays more and more important role in atmospheric composition sounding. Due to the high accuracy retrieval of trace gas in atmosphere, the accuracy of observation data should be very high which must be guaranteed critically by the superior performance of gas sensor. To achieve both high signal to noise ratio (SNR) and high spectral resolution, reasonable allocation and optimization of instrument parameters are the foundation and difficulty. According to the requirements of atmospheric detection spectrometer for space application, and based on operating principle of Michelson interferometer, the SNR and spectral resolution of time modulated FTS and their influencing factors have been simulated and analyzed. An optimum design method for key performance of FTS under low input radiance of weak scene has been present. The simulation model of FTS SNR has been built, which consider satellite orbit, spectral radiometric features of surface and atmospheric composition, optical system, interferometer and its control system, measurement duration, detector sensitivity, noise of detector and electronic system and so on. Spectral resolution is defined as the full width at half maximum (FWHM) of instrument line shape function (ILS) of spectrometer. The influence factors of ILS like maximum optical path difference (MPD) and field of view (FOV) of interferometer are analyzed. The design parameters of spectrometer has been optimized combining engineering feasibility, validated and analyzed with specific sample. Theoretical analysis and simulation results indicate that this model and method could be the basis of space borne time modulated Fourier transform infrared spectrometer design.