Patent ID: 9046674
Filing Date: 2015-06-02
Classification: G02B,G03B

Abstract:
1. A magnification optical system to form an enlarged image of an object, comprising: a refractive optical system including a plurality of lens groups; and a mirror train including a curved mirror, arranged in the following order from an object side; a first focus structure configured to move a part of the lens groups of the refractive optical system along a normal line of a conjugate surface on the object side while maintaining a distance between a conjugate-side lens surface of a lens of the refractive optical system closest to the object and the conjugate surface on the object side; and a second focus structure configured to change the distance between the conjugate-side lens surface of the lens of the refractive optical system closest to the object and the conjugate surface on the object side, wherein the second focus structure is fixed during operation of the first focus structure.