Patent ID: 11966043
Assignee: CANON KABUSHIKI KAISHA
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An imaging optical system comprising:
a plurality of reflecting surfaces that reflect light, and image a light flux emitted from an object plane on an image plane, the plurality of reflecting surfaces including at least a first concave reflecting surface, a convex surface, and a second concave reflecting surface, wherein light is reflected by the first concave surface, the convex surface, and the second concave surface, in this order; and
a plurality of adjusters configured to adjust a shape of each of the first and second concave reflecting surfaces by applying a force to a rear surface of each of the first and second concave reflecting surfaces,
wherein, in a state where correction points are obtained by projecting force acting points of the plurality of adjusters in an optical axis direction defined with respect to the first and second concave reflecting surfaces, the force acting points are set so that, among a first ray in a light flux emitted from a first point on the object plane and a second ray in the light flux emitted from a second point on the object plane different from the first point, and respectively reflected by the first concave reflecting surface and the second concave reflecting surface:
the first ray strikes the correction points of the first concave reflecting surface but does not strike the correction points of the second concave reflecting surface; and
the second ray does not strike the correction points of the first concave reflecting surface but strikes the correction points of the second concave reflecting surface, and

wherein the force acting points are set so that the correction points of the second concave surface are arranged at at least one of:
positions shifted from the correction points of the first concave surface in a radial direction centered on the optical axis; or
positions shifted from the correction points of the first concave surface in a circumferential direction centered on the optical axis.