Patent ID: 6747611
Filing Date: 2004-06-08
Classification: G02B

Abstract:
A compact optical system for directing an image signal for viewing by a user, the image signal being generated in accordance with a microdisplay, the system comprising:a beam splitting prism positioned proximate to the microdisplay; a field lens positioned between the beam splitting prism and the microdisplay; a negative lens positioned between the field lens and the beam splitting prism; a reflective lens positioned proximate to the beam splitting prism, on a side of the beam splitting prism opposite the microdisplay; and a quarter wave plate positioned between the reflective lens and the beam splitting prism; wherein the beam splitting prism, the field lens, the negative lens, the reflective lens and the quarter wave plate are arranged such that the image signal, linearly polarized in accordance with the microdisplay: (a) passes through the field lens and the negative lens; (b) enters the beam splitting prism substantially passing through a polarizing surface of the beam splitting prism; (c) passes through the quarter wave plate becoming circularly polarized; (d) reflects at a surface of the reflective lens back toward the quarter wave plate passing through the quarter wave plate a second time becoming linearly polarized with a polarization direction rotated by 90 degrees with respect to an original linear polarization direction associated with the image signal; and (e) reenters the beam splitting prism substantially reflecting at the polarizing surface of the beam splitting prism and exits the beam splitting prism for viewing by the user.