| By compensating random optical wavefront distortions real-timely, the adaptive optics (AO) system can hold the best working state in despite of the variable ambient. The wavefront corrector is one of the key elements of AO system. And improvement of the spatial correction capability of correctors is the primary coverage of AO theory and experiment research. In this dissertation, a kind of new adaptive optics configuration, in which several existing deformable mirrors (DMs) with optical conjugation relationships are equivalent to a new single corrector with more actuators to compensate high-order aberrations, is proposed. It is proofed that the combinational deformable mirror (CDM) technique can improve the spatial compensation capability of current AO system effectively. Based on the continuous surface DM with discrete axial piezoelectric actuators, the principles, the characters and the spatial compensation capability of CDM technique are studied in theory and experiment.First, the spatial character of continuous surface DM with discrete actuators is analyzed. The description of the surface displacement of DM is deduced and the limitation in linear superposition of Gauss influence functions is indicated. The relations between constructional parameter of DM and its spatial correction capability are analyzed. Results show that, with the increasement of the density of actuators, optimization of the Gauss index and the coupling coefficient, the correction capability can be effectively improved. And this result is verified in spatial frequency based on the principle of spatial filter. In addition, the stochastic parallel gradient (SPGD) algorithm is introduced into our work to optimize the actuator distribution of DM. And the optimized distributions for each order of 3-20 Zernike wavefront have been obtained, the results show that it is advisable to arrange some of the actuators around the out edge of the effective aperture.The configuration of combinational deformable mirror (CDM) is introduced in detail. Two DMs with square-array actuators or three DMs with triangle-array ones, even different kinds of DMs can be combined by 4F optical system to correct waverfront aberrations. The wavefront correction principle of CDM is analyzed and the analytic expression of its displacement has been deduced. Numerical calculation results show that the CDM is equivalent to one single DM with more actuators and larger coupling coefficient. Thus, the spatial compensation capability of CDM AO system can be improved effectively.The influence on spatial correction capability caused by axial and transversal matching errors of the CDM technique is analyzed. According to the theory of geometrical optics and diffraction optics it can be obtained that, the wavefront changes inconspicuously when a small aberration propagates with a large Fresnel Number and the 4F optical system can be left out from the CDM AO system, which is setup in laboratory. The analysis also proves that the CDM AO system is not sensitive to the spatial matching errors of DMs.Various existing control algorithms in multi-DM AO systems are compared. It is concluded that the direct-gradient control algorithm, which is widespreadly used in single DM AO system, is also suitable for CDM AO systems. Finally, the application prospect of CDM is discussed.The first CDM AO experimental system for wavefront correction is built up, which consists of two 32-element continuous surface discrete axial piezoelectric DMs with the square-array actuators. In the open-loop state, a definite surface displacement can be reconstructed. When this system works in closed-loop, static aberrations are compensated better than only by using one DM. The feasibility and advantage at improving spatial compensation capability of CDM AO systems are proved.In summary, the CDM AO system can improve the wavefront spatial compensation capability by increasing the actuators density or changing their distribution. This dissertation will provide some reference and experience for the design of DM and applications of CDM AO system.
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