| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a diffraction optical element in which shape evaluation can be easily performed. <P>SOLUTION: A diffraction optical element includes a diffraction grating 5 having a sectional shape of a sawtooth shape. A flat portion 51 is formed at the top of the diffraction grating 5 having the sawtooth shape. The proportion of a length of the flat portion 51 in a pitch direction of the diffraction grating 5 to the pitch of the diffraction grating 5 is preferably 5% or less. Further, the length of the flat portion 51 in the pitch direction of the diffraction grating 5 allows a measuring device for measuring a shape of the diffraction grating 5 to detect the flat portion 51. <P>COPYRIGHT: (C)2013,JPO&INPIT |
