| 摘要 |
A diffractive optical element is disclosed. The diffractive optical element is used in an illumination optical system of an exposure apparatus which exposes a substrate, and used for forming the intensity distribution of light at a pupil plane of the illumination optical system. The diffractive optical element comprises a first diffractive element and a second diffractive element which have different diffraction actions from each other, wherein each of the first diffractive element and the second diffractive element has point symmetry in a irradiated region where light is irradiated and common center of the point symmetry.
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