Patent ID: 7525735
Filing Date: 2009-04-28
Classification: G02B

Abstract:
1. A head mounted projection display (HMPD) optical lens assembly for transmitting and magnifying a real image to an eye comprising: (a) a miniature display, (b) a projection lens system for receiving the light rays from the display, (c) a second lens having a Fno between 0.1 and 3.0 positioned to receive the light rays from the projection lens for adjusting eye relief, (d) a beam splitter positioned for receiving and splitting the light rays from the second lens, (e) a retro-reflective screen positioned for receiving the a reflected portion of the split light rays from the beam splitter and then reflecting the portion of split light rays along a partially conjugate optical path relative to the incident light wherein the portion of split light rays passes through the beam splitter, (f) a third lens having a Fno between 0.1 and 3.0 positioned to receive the portion of split light rays from the retro-reflective screen that passes along a partially conjugate path and through the beam splitter, the third lens passing the light for viewing of the real image at the optical exit pupil by the, and (g) wherein the FOV is between 15 degrees and 50 degrees, said FOV having an overall distortion being less than 2.05% at the maximum point in the field, and the eye relief is between 15 mm to 50 mm.