Patent ID: 7557998
Filing Date: 2009-07-07
Classification: G02B

Abstract:
1. An optical system comprising: a lens system with a high degree of distortion at a relatively low angular FOV (field of view), said lens system comprising at least two groups of lenses, a first lens group facing an object space, and a second lens group closer to an image space of said lens, so that an aperture stop of said lens system is located between said lens groups and closer to the second lens group than the first lens group, wherein a distance of an entrance pupil of said lens system is larger than a distance from the first lens group to the aperture stop, and a ratio between an incident angle of a chief ray at a first surface of said second lens group and a chief ray angle at the entrance pupil increases non-linearly with angular field, thus producing a high degree of distortion across the field of view.