Being used by the luminous flux divergence element and luminous flux interference optical system and the luminous flux interference

摘要

PROBLEM TO BE SOLVED: To provide a novel light flux branching element which has simple structure and can also branch an incident light flux into four light fluxes.;SOLUTION: The light flux branching element for branching the incident light flux has arrangement of 1st to 4th area regions A to D as a substrate surface shape, wherein a X direction and a Y direction intersect orthogonally with each other on a plane and a Z direction is a direction orthogonally intersecting the plane. The 1st area region and the 3rd area region are alternately arranged in the Y direction, the 1st area region and the 4th area region are alternately arranged in the X direction and the 1st area region and the 2nd area region are alternately arranged in an oblique direction inclined to the Y direction. Size and an arrangement form of the 1st to 4th area regions A to D and an effective refractive index of each area region toward polarized light fluxes of X, Y directions are determined so as to act as a refraction grating in the Y direction toward the polarized light flux in the X direction and to act as a refraction grating in the X direction toward the polarized light flux in the Y direction.;COPYRIGHT: (C)2008,JPO&INPIT