| 摘要 |
The diffraction grating is a transmission-type diffraction grating having a repeating structure of projection and recess on at least one surface of a substrate. A sub-structure of which the cross section is approximated as a triangle or a trapezoid is provided in the recess. The height H of the projection and the height h of the sub-structure are set such that the ratio of the height h of the sub-structure to the height H of the projection is in the range of from 0.05 to 0.45. |
