Patent ID: 7477453
Filing Date: 2009-01-13
Classification: G02B

Abstract:
1. Optical system for image projection, particularly for projection devices of the “head-mounted” type, said system including: a display, an optical system for focusing an image formed by the display, a light guide having an extended body, with two opposite, longitudinal, plane and parallel faces, and opposite ends defining: a first reflecting surface for coupling into light guide, for reflecting through the light guide the light radiation exiting from said focusing optical system, and a second reflecting surface for extracting the image from the light guide, said light guide being shaped such that each light ray propagating into the light guide undergoes at least three internal total reflections on the parallel plane faces of said light guide; wherein: at least a surface of said focusing optical system is a portion of a surface free of rotational symmetry axes; the two reflecting surfaces of the light guide are portions of surfaces free of rotational symmetry axes; the inlet pupil of the light guide coincides with the outlet pupil of the focusing system; and wherein said focusing system is operable to perform a pre-distortion of the image formed by the display, to substantially compensate the residual aberrations introduced from the reflecting surfaces of the light guide; and wherein the focusing system is designed such that the coordinates i, j of each point of the image provided by the display are transformed in coordinates x, y such as: wherein: γ: is a parameter which controls the inclination of the horizontal lines, β: is a parameter which controls the factor of horizontal restaggering, α: is a parameter which controls the curvature of the vertical lines.