Efficiency of Blazed Diffractive Optics Produced by Diamond Turning

In blazed diffractive optics produced by the diamond turning process, the finite size of the tool causes a decrease in diffraction efficiency. To analyze the influence of the tool, we evaluate first-order diffraction efficiency of periodic gratings based on the electromagnetic theory. The design indices of the diffractive optics for higher efficiency are shown. Even with the same power of diffractive optics, the efficiency differs with the front or back side of the surface. The efficiency of a diffractive-refractive hybrid lens depends on the curvature of the refractive surface.