Patent ID: 7075722
Filing Date: 2006-07-11
Classification: G02B

Abstract:
1. A polarization converting element, comprising: a periodic first blazed type grating portion and a periodic second blazed type grating portion which is arranged on a light exit side of the first blazed type grating portion, wherein the first blazed type grating portion and the second blazed type grating portion are each formed by a plurality of grating sections, and a pair of grating sections corresponding to each other in each periodic first and second blazed type grating portions has the same period Pt, and each of the grating sections forming at least one of the first blazed type grating portion and the second blazed type grating portion is formed by a sub-wavelength structure grating having a period pl smaller than the period Pt, with the period p wherein light beams are diffracted by the first blazed type grating portion and the second blazed type grating portion at a specific diffraction order, and wherein said diffractive optical element is structured such that within an entire region of used wavelengths, diffraction directions are made different from each other, depending upon a polarization direction of a light beam incident on said diffractive optical element, and a diffracted light is concentrated only to one predetermined diffraction order, and further comprising deflecting means provided so that an emergence direction of one of a P-polarized light beam and an S-polarized light beam which has undergone polarization-separation to be diffracted in a diffraction direction different depending on a polarization direction by said diffractive optical element is made substantially coincident with an emergence direction of the other beam.