摘要 |
PROBLEM TO BE SOLVED: To provide a diffraction optical element which permits highly flexible design and has high efficiency of diffraction over a wide wavelength region. SOLUTION: The diffraction optical element 201 has a relief pattern formed on a surface of thereof, wherein a fine periodic structure 203 having a pitch shorter than the minimum wavelength of working wavelengths is formed on the relief pattern 202, and by changing parameters such as pitch, width and height (or depth) of the fine periodic structure 203, the wavelength dependency of effective refractive index in the fine periodic structure 203 is adjusted. As a result, the diffraction optical element 201 having the higher efficiency of diffraction on desired plural wavelengths or in a desired wavelength range is provided and the diffraction optical element designed more flexibly is provided. COPYRIGHT: (C)2008,JPO&INPIT
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