Schmid Tobias, Thompson Kevin P, Rolland Jannick P
CREOL, The College of Optics and Photonics, University of Central Florida, 4000 Central Florida Boulevard, Orlando, Florida 32816, USA.
Appl Opt. 2010 Jun 1;49(16):D131-44. doi: 10.1364/AO.49.00D131.
We present the effects of misalignments on the field dependence of the third-order aberration fields of traditional, two-mirror astronomical telescopes in the context of nodal aberration theory, which we believe is the most general and extensible framework for describing and improving on-station performance. While many of the advantages of nodal aberration theory, compared to other, often power series expansion-based descriptions of misalignment effects on aberrations, become particularly important when analyzing telescopes with more than two mirrors, or in the presence of figure errors; this paper aims to provide and demonstrate the fundamental concepts needed to fully describe the state of correction of misaligned two-mirror telescopes. Importantly, it is shown that the assumption that perfect performance on axis ensures a fully aligned telescope is false, and we demonstrate that if Ritchey-Chrétien telescopes are aligned for zero coma on axis as the sole criterion, formidable misalignments will likely remain, leading to image quality degradation, particularly beyond midfield caused by astigmatism with binodal field dependence (i.e., astigmatism goes to zero at two points in the field).
在节点像差理论的背景下，我们阐述了传统双镜天文望远镜的失调对三阶像差场的场依赖性的影响。我们认为，节点像差理论是描述和改进在轨性能的最通用、最具扩展性的框架。虽然与其他通常基于幂级数展开的失调对像差影响的描述相比，节点像差理论的许多优点在分析具有两个以上镜面的望远镜时，或在存在面形误差的情况下变得尤为重要；但本文旨在提供并论证充分描述失调双镜望远镜校正状态所需的基本概念。重要的是，结果表明，轴上完美性能确保望远镜完全对准的假设是错误的，并且我们证明，如果将里奇-克莱琴望远镜仅以轴上彗差为零进行对准作为唯一标准，可能仍会存在严重的失调，导致图像质量下降，特别是在中场以外，这是由具有双节点场依赖性的像散（即像散在视场中的两点处为零）引起的。
