| 摘要 |
A diffraction optical system comprises a free curve surface prism (14), and a multilayer diffractive optical element in which a plurality of diffractive element members (121, 122) are laminated together and a diffractive optical surface (DM) having a grating structure is formed at the interface thereof. The diffraction optical system further satisfies the following conditional expression: 0.005<(DeltaNg+DeltaNs)/2<0.45, where DeltaNg denotes a refractive index difference at g-line on the diffractive optical surface (DM), and DeltaNs denotes a refractive index difference at s-line on the diffractive optical surface (DM). |
