The Aberrations of Slightly Decentered Optical Systems*

Abstract

Two separate cases of aberrations due to decentration are discussed: In one, the field of view is small, and the aperture and spherical aberration are finite. In the other, the aperture is small, and the field of view, astigmatism, curvature of field, and distortion are finite. In either case, only small decentrations and tilts are admitted, and small quantities of order higher than the first are neglected. Since each member of the decentered system is itself a coaxial system, skew rays may be traced through each member with the aid of the laws of orthogonal systems. It is found that decentrations in a wide-aperture system give rise to coma, whereas in a wide-field system they give rise to a kind of distortion. A numerical example of each is given, and the resulting aberrations are compared to their third-order approximations.