Patent ID: 6927375

Claim:
An optical element, transmitting a light beam polarized in a first direction, and bending a traveling direction of light beam polarized in a second direction that is perpendicular to the first direction and diffracting the light beam polarized in a second direction, wherein the optical element generates a first diffraction light beam obtained by bending the traveling direction of an incident light beam polarized in the second direction and a second diffraction light beam, which is a +1-order diffraction light beam or a −1-order diffraction beam with respect to the first diffraction light beam comprising: a first diffraction element system for transmitting the light beam polarized in the first direction and diffracting all the light beam polarized in the second direction, and a second diffraction element for transmitting the light beam polarized in the first direction and diffracting the light beam polarized in the second direction at a predetermined efficiency, wherein the first diffraction element comprises a first light-transmitting material and a second light-transmitting material, a refractive index of the light-transmitting material and a refractive index of the second light-transmitting material are equal for the light beam polarized in the first direction and different for the light beam polarized in the second direction, an interface between the first light-transmitting material and the second light-transmitting material has a sawtooth groove shape, the second diffraction element comprises a third light-transmitting material and a fourth light-transmitting material, a refractive index of the third light-transmitting material and a refractive index of the fourth light-transmitting material are equal for the light beam polarized in the first direction and different for the light beam polarized in the second direction, an interface between the third light-transmitting material and the fourth light-transmitting material has a groove shape formed of periodic protrusions and depressions, and the first diffraction element and the second diffraction element are fixed to each other in a predetermined relative positional relationship.