Patent ID: 9625692
Date: 2017-04-18
CPC Classifications: G02B

Claim:
1. A projection optical system, comprising: a first optical system configured to form a first image conjugate to an object and have an optical axis; and a second optical system configured to project a second image conjugate to the first image onto a surface to be projected on, the surface extending in a horizontal direction and a vertical direction perpendicular to the horizontal direction, wherein the first image satisfies a condition of: wherein Im denotes a length of the first image in a direction of an optical axis of the first optical system, normalized by a focal length of the first optical system; and Tr denotes a throw ratio for the projection optical system, wherein a TV distortion in the second image is less than or equal to 3%, wherein the second optical system includes a single mirror with a refractive power, wherein the horizontal direction and the vertical direction are normal to the first optical system, and wherein the throw ratio Tr is a ratio of a projection distance of the projection optical system to a length of the second image in the horizontal direction.