Separation of the effects of astigmatic figure error from misalignments using Nodal Aberration Theory (NAT)

Tobias Schmid,Jannick P Rolland,Andrew Rakich,Kevin P Thompson

doi:10.1364/oe.18.017433

Abstract

We present the nodal aberration field response of Ritchey-Chrétien telescopes to a combination of optical component misalignments and astigmatic figure error on the primary mirror. It is shown that both astigmatic figure error and secondary mirror misalignments lead to binodal astigmatism, but that each type has unique, characteristic locations for the astigmatic nodes. Specifically, the characteristic node locations in the presence of astigmatic figure error (at the pupil) in an otherwise aligned telescope exhibit symmetry with respect to the field center, i.e. the midpoint between the astigmatic nodes remains at the field center. For the case of secondary mirror misalignments, one of the astigmatic nodes remains nearly at the field center (in a coma compensated state) as presented in Optics Express 18, 5282-5288 (2010), while the second astigmatic node moves away from the field center. This distinction leads directly to alignment methods that preserve the dynamic range of the active wavefront compensation component.

Highlights

Nodal aberration theory for optical imaging systems without symmetry has emerged as an effective approach to describe the aberrations in misaligned or intentionally decentered/tilted optical systems [1,2,3]
We present the nodal aberration field response of RitcheyChrétien telescopes to a combination of optical component misalignments and astigmatic figure error on the primary mirror
The work is based on the wave aberration theory of Hopkins [5], the concept of shifted aberration field centers attributed to Buchroeder [6], and a key insight from Shack [7] that combined lead to the discovery that many of the traditional aberration fields become multinodal when symmetry is broken

Summary

Introduction

Nodal aberration theory for optical imaging systems without symmetry (but with rotationally symmetric components) has emerged as an effective approach to describe the aberrations in misaligned or intentionally decentered/tilted optical systems [1,2,3]. Recommended Citation Schmid, Tobias; Rolland, Jannick P.; Rakich, Andrew; and Thompson, Kevin P., "Separation of the effects of astigmatic figure error from misalignments using Nodal Aberration Theory (NAT)" (2010).

Results

Conclusion