| 摘要 |
A diffractive optical element includes multiple diffraction gratings laminated and made of at least three material types, wherein the multiple diffraction gratings include: a first combination part including two diffraction gratings of materials different from each other in which grating side surfaces of grating parts contact with each other or are disposed close to each other in a grating pitch direction; and a second combination part including two diffraction gratings of materials different from each other in which at least one material is different from the materials of the first combination part; and when N1Aw and N1Bw denote refractive indices of the first combination part at a wavelength (w),ν1A andν1B denote Abbe numbers, N2Ad and N2Bd denote refractive indices of the second combination part on a d-line,ν2A andν2B denote Abbe numbers, the wavelength (w) is 370<w<730 (nm). The followings are satisfied: N1Aw−N1Bw=0; 16<(ν1A−ν1B)<75; 0.03<|N2Ad−N2Bd|<0.5; and 16<(ν2A−ν2B)<75.
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