Among all kinds of wavefront control algorithms in adaptive optics systems, the direct gradient wavefront control algorithm is the most widespread and common method. This control algorithm obtains the actuator voltages directly from wavefront slopes through pre-measuring the relational matrix between deformable mirror actuators and Hartmann wavefront sensor with perfect real-time characteristic and stability. However, with increasing the number of sub-apertures in wavefront sensor and deformable mirror actuators of adaptive optics systems, the matrix operation in direct gradient algorithm takes too much time, which becomes a major factor influencing control effect of adaptive optics systems. In this paper we apply an iterative wavefront control algorithm to high-resolution adaptive optics systems, in which the voltages of each actuator are obtained through iteration arithmetic, which gains great advantage in calculation and storage. For AO system with thousands of actuators, the computational complexity estimate is about O(n2) ～ O(n3) in direct gradient wavefront control algorithm, while the computational complexity estimate in iterative wavefront control algorithm is about O(n) ～(O(n)3/2), in which n is the number of actuators of AO system. And the more the numbers of sub-apertures and deformable mirror actuators, the more significant advantage the iterative wavefront control algorithm exhibits.
We proposed a wide spectrum and rapid calculation model FALTRAN( Fast Atmospheric Limb TRANsmission),to solve the problems of current radiative transfer model in limb remote sensing. In FALTRAN:( 1) Band model algorithm was employed and the molecular spectroscopy database was based on HITRAN2008.( 2) Limb radiative transfer equation consists of scattering and thermal radiation was established,and according to the limb geometry characteristic,a Hemisphere Radiation Adding( HRA) approach based on finite difference method was proposed to solve it. We investigated the atmospheric limb radiations under typical atmospheric modes in several commonly used remote sensing bands. Moreover,radiation contribution by two hemispheres was quantitative analyzed as well. Validation results show that the relative differences between FALTRAN and Combining Differential-Integral( CDI) model are within 2%,and calculation results by FALTRAN have good agreement with Michelson Interferometer for Passive Atmospheric Sounding( MIPAS) measurements. FALTRAN is proven to be reliable in the limb radiative transfer calculation.
