一种液晶相控阵中基于迭代的相位恢复算法

An Iteration-Based Phase Retrieval Algorithm in Liquid-Crystal Phased Array

在液晶相控阵中,由于电压量化、边缘效应、液晶器件制造工艺等因素的影响,导致实际的波前相位面与理想的波阵面存在误差。因此,在应用中要依据实际出射相位与理想出射相位的偏差,反复地修正加载电压,对入射激光波前进行相位调制,以此来满足视场域内波束扫描的需要,这也是液晶相控阵波束控制技术研究的关键问题。为解决上述问题,提出了一种波前相位恢复算法。该算法利用三个输出面的幅度信息迭代计算出波前相位分布,相比只用两个输出面幅度信息的相位恢复算法,该算法具有较高的精确度。同时,该算法利用角谱理论处理输出面的光场传播过程,使得所得到的恢复结果更加精确。仿真实验进一步表明,这种算法在精确度、效率上同时具有优势。

In liquid-crystal phased array, the actual wavefront may deviate from the ideal wavefront, since the actualperformance depends significantly on voltage quantization, phase sag, fringing effect, the manufacturing process ofliquid crystal device, and so on. Thus, to meet the requirement of beam scanning in the view field, the voltage isconstantly adjusted according to deviation between the actual wavefront phase and the ideal, such that the actualphase can approximate to the ideal phase as much as possible. This has been one of the key problems in liquid crystalphased array. For retrieving the phase in liquid crystal phased array, a novel output-plane-based phase retrievalalgorithm with wavefront iteration is presented. Specifically, the wavefront phase distribution is retrieved by usingthe knowledge of intensity measurements in three output-planes. Compared with the algorithms depended on the twooutput planes, our algorithm can achieve high precision. Moreover, the algorithm exploits angular spectrum transferfunction, thus the results are more reliable. The theoretical analysis and simulation experiments indicate that thisalgorithm enjoys advantages in terms of precision and efficiency simultaneously.