Patent ID: 9007497
Filing Date: 2015-04-14
Classification: G02B,H04N

Abstract:
1. A reflective objective optical system for forming an image at a first image plane of an object in an object space for light rays having at least one waveband, consisting of: a first mirror, a second mirror and a third mirror arranged in three-mirror anastigmat configuration and having respective first, second and third reflective surfaces that reflect the light rays from the object to the image in order from the first reflective surface to the second reflective surface to the third reflective surface, wherein the light rays include central rays that are substantially parallel when incident upon the first mirror and that are not substantially parallel when reflecting from the third mirror; at least one intermediate image location between the first and third mirrors and where at least one intermediate image is formed; and wherein the first, second and third reflective surfaces have different toroidal non-rotationally symmetric asphere shapes, with the first, second and third reflective surfaces having respective centers of curvatures that do not lie along a common axis.