| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a diffraction grating that allows an efficiency of diffraction to be highly kept even if a ridge part of a projection thereof is not pointed. <P>SOLUTION: A diffraction optical element 1 includes a first optical member 10 and a second optical member 11, both of which are laminated. A diffraction grating 13 is formed on a boundary surface 12 between the first optical member 10 and the second optical member 11. A first diffraction grating 14 of the first optical member 10 is constituted in arrangement of multiple projections 14a made up of a vertical plane 14b and an inclined plane 14c. A second diffraction grating 15 of the second optical member 11 is constituted in arrangement of multiple valley-shaped recesses 15a fitted in with the projections 14a. A ridge part 14d of the projections 14a is made a curved plane. A curvature radius R (μm) of the curved plane, a pitch P (mm) of the projections and a difference Δn<SB POS="POST">d</SB>between the refractive indices of the first optical member 10 and second optical member 11 satisfies a predetermined relation. <P>COPYRIGHT: (C)2012,JPO&INPIT |
