Polarization selecting prism for a projection device

摘要

A prism separating and synthesizing a light beam of a wide angle of incidence. A diffraction prism 15 of embodiments of the present invention is so constructed that a diffraction grid 21 is sandwiched between a pair of diffraction grid substrates 22, a pair of prism substrates 24 are bonded to the surfaces of the prism substrates 22 facing the diffraction grid 21 with interposition of adhesive layers 23, and a diffraction grid medium 25 having a refractive index substantially equal to that of the prism substrates 24 is charged in a gap defined by the diffraction grid 21 and the prism substrates 24, with the respective component members being optically combined together. An incident light is led to the diffraction grid 21 and separated on transmission or reflection by the operation of diffraction by the diffraction grid 21. <IMAGE>