阐述了基于相位差法(PD)的波前误差传感技术的基本原理,针对该方法的优化目标函数非线性度较高等特点,提出了基于遗传算法(GA)的改进相位差法。对遗传算法的基本特点进行了分析,遗传算法因其高效、并行和全局搜索等特性,非常适合对相位差法的全局寻优。建立了由三个子镜组成的稀疏孔径系统,给各子镜加入不同的活塞光程差,分析了其优化目标函数的变化情况,并采用遗传算法对该函数进行了全局寻优。通过实验模拟结果表明,遗传算法可寻得系统的全局最优值,其所寻得的活塞误差估计值与真实活塞光程差的均方根(RMS)可以达到0.04λ,具有较高的传感精度。

The basic principles of wave-front sensing based on phase diversity (PD) are expatiated. An improved PD based on genetic algorithm (GA) is proposed for the highly nonlinear character of PD′s objective function. The parallel and global search features of GA are suitable for the global optimization of PD by analyzing the characters of GA. A sparse-aperture system composed by three sub-apertures with different piston errors is established. The changes of the optimization objective function are analyzed and the new PD based on GA is used to find the global optimal value of the system. The results of many experimental simulations show that:GA can find the global optimum value of the sparse-aperture system,and the root mean square (RMS) between estimated piston error found by GA and the true piston error is 0.04λ. The new PD has a high accuracy.