失调卡塞格林光学系统像差特性的研究

Misalignment induced aberration characteristic of Cassegrain telescope

以矢量波像差理论为基础,对卡塞格林光学系统的失调像像差特性进行分析,通过分析发现失调的卡塞格林系统不会引入新的像差,只是会导致三阶像差在像面上的分布发生变化,球差在全视场内为常量,彗差零点不再位于视场中心,像散在视场内存在两个零点且不再关于中心视场对称。在校正失调产生轴上彗差的情况下,卡塞格林系统的一个像散零点位于轴上视场,轴上视场的像差接近于零,但是边缘视场的像散依然较大,因此在卡塞格林系统的装调过程中,需要测量多个视场的波像差来确定系统的装调状态。利用CODE V对失调卡塞格林系统的像差在视场上的分布进行仿真,结果表明利用矢量波像差理论可以对失调卡塞格林系统的像差进行定性分析,以提高卡塞格林系统的装调效率。

Based on the vector wavefront aberration theory, the misalignment induced aberration′ s characteristic of Cassegrain optical system was analyzed in this paper. It is shown that a misaligned Cassegrain has three residual 3rd aberrations. The 3rd order spherical aberration is constant over the field and the 3rd order coma increases linearly with the field but the zero coma point no longer locates at the field center. Moreover, the astigmatism aberration field in system without symmetric contains two zero astigmatism point, neither of which is necessarily located on the field center of view. It has been demonstrated that a Cassegrain under assembly is only measured to have perfect performance on-axis but not aligned in any significant way, so the measurements of multiple field points for the Cassegrain are required in the process of alignment.