The Greenwood frequency (GF) is influential in performance improvement for the coherent free space optical communications (CFSOC) system with a closed-loop adaptive optics (AO) unit. We analyze the impact of tilt and high-order aberrations on the mixing efficiency (ME) and bit-error-rate (BER) under different GF. The root-mean-square value (RMS) of the ME related to the RMS of the tilt aberrations, and the GF is derived to estimate the volatility of the ME. Furthermore, a numerical simulation is applied to verify the theoretical analysis, and an experimental correction system is designed with a double-stage fast-steering-mirror and a 97-element continuous surface deformable mirror. The conclusions of this paper provide a reference for designing the AO system for the CFSOC system.

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We developed a new method for interpretation of airborne gravity gradiometry data, based on cokriging inversion. The cokriging method that we evaluated minimized the theoretical estimation error variance by using auto-and crosscorrelations of several variables. It does not require iterations and can easily include complex a priori information. Moreover, the smoothing effects in the inverted density structure model can be reduced to a certain extent due to the anisotropy constrain in the covariance model. We compared the recovered models obtained by inverting the different combinations of gravity-gradient components to understand how different component combinations contributed to the resolution of the recovered model. The results indicated that including multiple components for inversion increased the resolution of the recovered density model and improved the structure delineation. Moreover, in the case in which the parameters of the variogram model are not well chosen, cokriging with multicomponent combinations can still correctly recover the geometry of the targeted sources. The survey data of the Vinton dome were considered as a case study. The results of the inversion were in good agreement with the known formation in the region. This supports the validity of our method.