Research on a Decoupling Algorithm for a Dual-Deformable-Mirror Wavefront-Correction System

Wavefront distortion caused by atmospheric turbulence can be described as different types of aberrations, such as piston, tilt, defocusing, astigmatism, coma, etc. Dual-deformable mirrors can have mutual coupling effects that help correct the effects of wavefront distortion. In this study, a fast-steering mirror (FSM) and a deformable mirror (DM) were used to form a dual-deformable-mirror wavefront-correction system, and a decoupling algorithm that could correct any specified aberration was proposed. In this decoupling algorithm, both the FSM and the DM are controlled using the mode method, and specific aberrations are corrected based on a limited matrix. The DM-compensation ability is directly characterized by the mode coefficients of the aberrations; thus, it can independently correct any order of aberration and effectively reduce the coupling effect of the wavefront-correction system. An experiment using an adaptive-optical dual-deformable-mirror wavefront-correction system was conducted to verify the proposed decoupling algorithm. When the FSM corrects the first- and second-order aberrations, and the DM corrects the third-, tenth-, and 25th-order aberrations, the coupling coefficients are approximately 1.117 × 10−3, 1.824 × 10−2, and 7.81 × 10−3, respectively, and the magnitude of the coupling coefficients reaches 10−2 and below. The experimental results show that the decoupling algorithm can effectively suppress the coupling effect between the FSM and DM.