Patent ID: 6246516
Filing Date: 2001-06-12
Classification: G02B

Abstract:
An afocal optical system defining an intermediate image plane and a real exit pupil, the afocal optical system comprising:an objective having a focal length and defining an optical axis;said objective having a structural length and being configured as a telesystem including a positive front group and a negative rear group;said positive front group and said negative rear group conjointly defining a telefactor (TF) of less than 0.7 wherein said telefactor is the ratio of said structural length of said objective to said focal length thereof;an ocular defining a focal length and including at least two lenses arranged on said optical axis;said image plane and said real exit pupil defining a distance therebetween and said distance being greater than said focal length of said ocular by a factor of at least 1.3; and,a plurality of lenses arranged in front of said negative rear group and being exchangeable for changing the magnification of said system.