| 摘要 |
A diffractive optical element 1 comprises a first element 10 and a second element 20 , whose materials are different from each other. These elements are bonded to each other, with a diffraction grating 30 created on the boundary surface between the first element 10 and the second element 20 , and in the diffractive optical element 1 , at least the second element 20 is made from a photo-setting resin, which is set by light rays incident through the first element 10 . The diffractive optical element 1 is set in a predetermined range of values including values that make the transmittance T1 of the first element 10 and the transmittance T2 of the second element 20 equal to each other for the light rays. As a result, as differences in cure shrinkage in the second element 20 are generated by differences in the intensity of the light rays caused from ups and downs of the diffraction grating 30 created on the surface of the first element 10 , the differences in cure shrinkage are controlled within a range so as not to degrade the desired performance of the diffractive optical element 1.
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