High spectral resolution lidars (HSRLs) designed for climate study are increasingly being deployed on aircraft and called for on future space-based missions in remote sensing of aerosol and cloud. The HSRL relies on spectral discrimination of the atmospheric backscatter signals to enable independent, unambiguous retrieval of aerosol extinction and backscatter. In this paper, by the review of specifications and performance of the Fabry-Perot Etalons as the spectral filter, a comprehensive conceptive study is being proposed and developed to replace the existing Fabry-Perot Interferometer (FPI) with Doppler Michelson Interferometer (DMI). Furthermore, the possibility of the utilization of the spatial heterodyne spectrometer (SHS) as an innovative approach for new development of the spectral filter and light detector in the new HSRL system is introduced and discussed. Similar to the DMI, a compact, monolithic field-widened spatial heterodyne interferometer with differential arms is designed to optimize thermal compensation such that the maximum interference can be obtained with great precision to the transmitted laser wavelength. Both field widened DMI and SHS has superiority (throughput) advantage over the FPI in spectral perspective, but the SHS provide more flexibilities and stabilities to ease construction and operation. The comprehensive preliminary optical design of such a field-widened spatial heterodyne interferometer for the HSRL includes the simulation of the angular distribution and finite cross sectional area of the light source, reflectance of all surfaces, loss of absorption, and lack of parallelism between the two differential arms, etc. The new design can also be used to assess the performance of the spatial heterodyne interferometer and thus it is a useful tool to evaluate performance budgets of the new filter and detector and to set optical specifications for new designs of the HSRL. Since the modularization and miniaturization of the SHS with possible multiple band capacity would be available in near future, it is our hope that further study on such a SHS module would be beneficial to the new development of the HSRLs.
© 2013 Optical Society of AmericaPDF Article