| 摘要 |
A diffraction optical element is provided to reduce harmful lights and also suppress deterioration in the optical characteristics of the element. The diffraction optical element 22 is formed with a plurality of diffraction gratings 17′, 18′, 19′ and 20′. From these diffraction gratings, there are selected the diffraction gratings 18′, 19′ and 20′ whose groove apex angles are less than a predetermined angle. The diffraction gratings 18′, 19′ and 20′ has chamfer surfaces 18c′, 19c′ and 20c′ formed on the lower side of respective slanted surfaces 18a′, 19a′ and 20a′. The chamfer surfaces 18c′, 19c′ and 20c′ are slanted to the slanted surfaces 18a′, 19a′ and 20a′, respectively.
|
