基于傅里叶光学的基本原理和稀疏孔径光瞳结构,建立了子镜与衍射拼接主镜厚度误差间的关系模型。在子镜无衍射结构一侧微变形情况下,给出了任意低阶面形误差引入的相位差的一般表达式。以球面变形为例,分析计算了面形误差的容许范围,并采用ZEMAX光线追迹法对结果进行了交叉验证。对于子镜双侧无变形的特殊情况,运用蒙特卡罗方法讨论了子镜间厚度的一致性对拼接主镜成像质量的影响,给出了正态分布条件下衍射拼接主镜相干成像时子镜厚度误差的方差与极值范围。根据理论设计结果加工了两片离轴衍射子镜,开展了双子镜拼接成像性能实验。实验结果表明,衍射拼接主镜能提高等效分辨率。

Based on the basic principle of Fourier optics and the pupil configuration of sparse aperture system, the relationship model of the thickness error between the sub-aperture and the diffractive segmented lens is established. The general expression of the phase difference induced by an arbitrary low-order surface shape error is presented under the condition of micro-deformation on one side of the sub-aperture which is without diffraction structure. Taking the spherical deformation as an example, the tolerance range of the surface shape error is discussed and calculated, and the results are verified by the ZEMAX ray tracing method. As for the special case that there is no deformation on both sides of the sub-aperture, the Monte Carlo method is used to investigate the effect of the thickness uniformity among these sub-apertures on the imaging quality of the segmented primary lens and the variance and extreme range of the sub-aperture thickness error are obtained when the coherent imaging is made by the diffractive segmented lens under a normal distribution. According to the theoretical design results, two off-axis diffractive sub-apertures are fabricated and the experiment on the segmented imaging performance of dual sub-apertures is conducted. The experimental results show that the diffractive segmented primary lens can improve the equivalent resolution.