对于大气湍流引起的波前畸变,现有波前重建方法的分辨率低,并受传感器和变形镜的结构限制,基于此,提出一种基于小波分形差值波前校正的方法。该方法是在对大气湍流引起的波前畸变进行自相似分析的基础上,利用小波分形插值方法进行波前重建的一种方法。首先采用快速小波分解法对波前相谱进行多分辨率分析,并在此过程中进行软阈值去噪;然后用分形插值方法提高波前相位的分辨率;最后采用快速小波重构方法恢复波前相位。实验结果表明:与基于最小方差估计(MVE)方法相比,采用快速小波重构法恢复波前相位的光强值与残余波前方均根均显著提高,能有效减少噪声的干扰,得到较高的成像质量,校正后的光斑形态良好,稳定性较高。

Existing wavefront reconstruction methods generally have low resolution when we examine wavefront distortion caused by turbulence in the atmosphere. They are also limited by the structures of sensors and deformable mirrors. In this paper, a method based on wavelet fractal-difference wavefront correction is proposed. A wavefront reconstruction method based on wavelet fractal interpolation is also proposed, and it is applied after performing self-similarity analysis of wavefront distortion caused by atmospheric turbulence. The multi-resolution analysis of the wavefront phase spectrum is performed by the fast wavelet decomposition method and soft threshold denoising is performed in this process. Subsequently, the fractal interpolation method is used to increase the resolution of the estimated wavefront phase. Finally, the recovery of the wavefront phase is achieved by applying the fast wavelet reconstruction method. Experimental results show that the fast wavelet reconstruction is capable of recovering the wavefront phase. Compared with the minimum variance estimation (MVE) method, the proposed method improves the light intensity value and residual wavefront root-mean-square value, thereby effectively reducing noise interference. A higher imaging quality is obtained and the corrected spot shape is reliable and stable.