扩展目标夏克-哈特曼波前传感器(SH-WFS)子图像之间偏移量的计算是影响波前传感精度的关键，通常采用相关算法来实现，并通过抛物线插值达到亚像元精度。子图像间的相对偏移量计算也可采用频域相移量估算的方法进行计算，频域算法还可通过迭代进一步提高算法精度。对频域迭代算法进行了理论分析、仿真和实验研究，结果表明，频域迭代算法在信噪比高于41时，具有比抛物线插值法更高的计算精度；在信噪比较低时，与抛物线插值法精度相近。

The estimation of the shifts between sub-images obtained in extended scene Shack-Hartmann wavefront sensing (SH-WFS) are the keys for calculating wavefront errors. The estimation can be got by parabolic interpolation algorithm and the accuracy can reach sub-pixel. The estimation can also be acquired by frequency-domain phase-shift algorithm and the accuracy can increase using frequency-domain iterative algorithm. Based on the later algorithm, the theoretical analysis, simulation and experiment are researched. The results show that the parabolic interpolation algorithm and frequency-domain iterative algorithm get close results in low signal-noise-ratio (SNR), but the later one performs better while SNR is higher than 41.