| 摘要 |
A wavelength-selective polarizing diffraction element functioning as a polarizing diffraction element at a wavelength lambda1 but not functioning as a diffraction lattice at a wavelength lambda2 despite an incident polarization state, and having a high transmittance; and an optical head device using it. The polarizing diffraction element selectively diffracts or transmits, according to the wavelength and polarization state of an incident light, at least two incident lights having different wavelengths that respectively have a first circular polarization and a second circular polarization providing rotation reverse to that of the first circular polarization. The wavelengths of the two incident lights are not included in at least a reflection wavelength band relative to an incident light having the first circular polarization.
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