Patent ID: 8189264

Claim:
A projection optical system, in which a plurality of light flux emitted from one conjugate plane enters another conjugate plane and an image formed on the one conjugate plane is projected on the other conjugate plane, comprising: a first optical system including at least one lens; and a second optical system which includes at least a first reflecting surface and a second reflecting surface, each with optical power, wherein the first reflecting surface receives the light flux directly from the first optical system, wherein the second reflecting surface reflects the light flux to the other conjugate plane, wherein a normal line of the other conjugate plane from a center of an image projected on the other conjugate plane has no intersection with any space of the first optical system, or the second optical system, or a space between the first optical system and the second optical system, and wherein when a plane defined by a vertical direction of the image projected on the other conjugate plane and an extending direction of the normal line is set as a YZ plane, the light flux reflected by the second reflecting surface intersects only once with an optical path from the first optical system to the first reflecting surface on the YZ plane.