A spectroscopic transmittance analytical modeling for field-widened Michelson interferometer employed by high spectral resolution lidars

摘要

High spectral resolution lidars (HSRLs) have shown great advantages for the measurement of backscatter and extinction coefficients of aerosols and clouds due to its spectral discrimination process, which brings about more straightforward and accurate retrieval without additional assumptions in contrast to standard backscatter lidars. We have developed a tilted, field-widened Michelson interferometer (FWMI) to obtain this spectral discrimination. The interferometer is composed of a cubic beam splitter, a solid arm and an air-solid blending arm, and will be employed as the spectroscopic filter of an HSRL to block the aerosol signals but transmit the molecular backscattered photons optimally. In this paper, a comprehensive radiometric model is developed to evaluate the spectral discrimination performance of the FWMI, especially under varies of practical imperfections, such as fabrication errors and utility defections. The principle of the modeling for tilted FWMI as the spectroscopic filter of the HSRL has been presented, through which, the effects on transmittance characteristics of the FWMI from these practical imperfections are analyzed in detail. The model can be used to evaluate the machinery tolerance budgets for new FWMI designs and decide optimal state of usage for FWMI appliance.