Catadioptric optical system and image pickup apparatus having the same

摘要

A catadioptric optical system includes a first imaging optical system that includes a catadioptric part that collects a light beam from an object to form an intermediate image of the object, and a second imaging optical system that includes a refractive part that images the intermediate image on an image plane. The first imaging optical system includes a first optical element, a second optical element, and a negative lens in an optical path between the first and second optical elements, and the first and second optical elements are disposed so that reflection parts of the first and second optical element face each other. A power φn of the negative lens, radii of curvature R1n and R2n of lens surfaces of the negative lens at an object side and an image side, respectively, and a power φ1 of the first imaging optical system are appropriately set.

主权项

1. A catadioptric optical system comprising:
a first imaging optical system that includes a catadioptric part configured to collect a light beam from an object to form an intermediate image of the object; and a second imaging optical system that includes a refractive part configured to image the intermediate image on an image plane, wherein the first imaging optical system includes a first optical element having a light transmission part around an optical axis and a reflection part including a surface as a reflection surface provided at an outer circumference side relative to the light transmission part and disposed at the object side, a second optical element having a light transmission part around the optical axis and a reflection part including a surface as a reflection surface provided at an outer circumference side relative to the light transmission part and disposed at the image side, and a negative lens in an optical path between the first optical element and the second optical element, the first optical element and the second optical element being disposed so that the reflection part of the first optical element and the reflection part of the second optical element face each other, wherein the light beam from the object emits to a side of the second imaging optical system via the light transmission part of the first optical element, the negative lens, the reflection part of the second optical element, the negative lens, the reflection part of the first optical element, the negative lens, and the light transmission part of the second optical element, in order, and wherein the following expressions are met:
0.1<|φn/φ1|<0.30.3