| 摘要 |
PURPOSE:To improve the light use efficiency without blazing a diffraction grating by varying the width and height of a grating projecting part in accor dance with a pitch of the grating projecting part which is varied gradually toward the outside from the center of a lens. CONSTITUTION:The titled grating lens consists of a concentric circle-like grating projecting part 1 whose cross section shape is rectangular or similar to a rectangle, and a surface relief diffraction grating having a concentric circle-like groove part 2 which has been placed between said parts 1, and in accordance with a pitch (d) of the grating projecting part 1 which is varied gradually toward the outside from the center of a lens, width (w) and height (h) of the grating projecting part 1 are varied. In such a way, the use efficiency of light can be improved without blazing the diffraction grating. |
