| 摘要 |
PROBLEM TO BE SOLVED: To provide a wavelength plate usable in a wide wavelength band and showing excellent durability even when used for a projection display device. SOLUTION: The wavelength plate 1 has a grating part 4 with two kinds of media A (2) and B (3), with mutually different wavelength dispersion of refractive indexes, alternately arranged in stripes with a period shorter than the wavelength of the light and the media are selected in such a way that the refractive index of the medium A is larger than that of the medium B and further the wavelength dispersion of the refractive index of the medium A is smaller than that of the medium B. |
