Optical element, optical functional device, polarization conversion device, image display apparatus, and image display system

摘要

The present invention discloses various embodiments of optical elements each having a plurality of periodic structures in which each period is smaller than the wavelength of usable light. For example, there are disclosed an embodiment in which a desired phase difference can be obtained at at least two wavelengths in a used wavelength region, an embodiment in which periodic directions of a plurality of structures are perpendicular to each other, and an embodiment in which the difference in refractive index between individual structures for a predetermined polarization component is set to a predetermined value or less.