Patent ID: 6903881

Claim:
A projection optical system for enlarging and projecting an image of an image display element onto a screen comprising: a first prism that includes an incident light refracting surface for receiving light from the image display element, said incident light refracting surface being the incident light refracting surface of the projection optical system; a second prism that includes an exit light refracting surface for emitting light toward the screen, said exit light refracting surface being the exit light refracting surface of the projection optical system; and prism internally reflecting surfaces having optical power arranged so that light that enters said incident light refracting surface from the image display element is reflected at least six times before exiting said exit light refracting surface; wherein the projection optical system does not form an intermediate image of the image display element between said incident light refracting surface and said exit light refracting surface; and the projection optical system can operate with finitely separated conjugates without any additional converging optics.