A novel method of measuring the interaction matrix for diffractive liquid crystal wavefront correctors

•The TC method decreases the effect of the diffraction wavefront error on the interaction matrix.•The LS method is combined with the TC method to eliminate the effect of the random error.•A considerable improvement of the image resolution was obtained by the novel method.•This method is very useful for LC AOSs to acquire the high correction accuracy.

The interaction matrix significantly affects the correction accuracy of wavefront correctors. For diffractive liquid crystal wavefront correctors (LCWFCs), the diffraction wavefront error must be taken into account to improve the accuracy of the interaction matrix. In this paper, a tunable Zernike polynomial coefficient method is demonstrated that decreases the effect of the diffraction wavefront error on the interaction matrix. Moreover, to eliminate the effect of the random error, a least squares method is combined with the tunable coefficient method. Experimental results show that, with the combined method, the error of the interaction matrix is decreased by a factor of 2.5 compared to that when the least squares method is used alone. Furthermore, an open loop adaptive correction experiment was performed and a considerable improvement of the image resolution was obtained by the novel method. Therefore, this method is very useful for liquid crystal adaptive optics systems to acquire the high correction accuracy.