Patent ID: 7976166

Claim:
An optical system for image projection comprising: a converging optical system which converges a light flux from a light source toward a reflective image-forming element; and a polarization beam splitting surface which transmits an incoming light flux having a first polarization direction, of the light flux from the converging optical system, to introduce it to the reflective image-forming element and causes light having a second polarization direction perpendicular to the first polarization direction, of an outgoing light flux from the reflective image-forming element, to proceed to a projection optical system, wherein the converging optical system includes a lens array which divides the light flux from the light source into plural light fluxes, a polarization conversion element which converts non-polarized light from the lens array into linearly-polarized light having a certain polarization direction and a condenser lens which superposes the plural light fluxes from the polarization conversion element on the reflective image-forming element, and wherein, in a first cross-section which is parallel to a normal to the polarization beam splitting surface and a normal to an entrance/emergence surface of the reflective image-forming element, the converging optical system has a configuration which causes an incident angle on the polarization beam splitting surface of a light ray passing through a barycenter of intensity distribution of the outgoing light flux to be larger than an incident angle on the polarization beam splitting surface of a light ray passing through a barycenter of intensity distribution of the incoming light flux, the configuration being one of a configuration in which the lens array and the polarization conversion element are decentered with respect to the condenser lens, the polarization beam splitting surface and the reflective image-forming element and a configuration in which the lens array and the polarization conversion element are inclined with respect to the normal to the entrance/emergence surface.