Patent ID: 7518794

Claim:
A transmission diffraction optical element comprising: a substrate layer; a plurality of parallel ridge-shaped projections formed in a periodic pattern and disposed on the substrate layer, said ridge-shaped projections having roughly rectangular cross-section shapes perpendicular to a longitudinal axis; a plurality of parallel striped thin-film layers with a uniform composition being arranged at a pitch matching a pitch at which said ridge-shaped projections are arranged and with an orientation identical to an orientation of an arrangement of said ridge-shaped projections, said plurality of parallel striped thin-film layers formed parallel to said substrate layer and at a fixed distance from said substrate layer or on a plane parallel to said substrate layer with a boundary surface within said ridge-shaped projections; and a thin-film layer being disposed parallel to said substrate layer, having a boundary surface either parallel to the surface of said substrate layer or on said substrate layer, and formed with a uniform composition within a plane parallel to said substrate layer, said thin-film layer being formed without a periodic pattern in a direction identical to that of said periodic pattern of said ridge-shaped projections and having wavelength-selective transmission properties; wherein said striped thin-film layers are disposed on top surfaces of said ridge-shaped projections and on bottom surfaces of grooves between said ridge-shaped projections.