| 摘要 |
<p>Provided is a structural double-refraction quarter-wave plate, which has a concavo-convex period structure of a relatively long structural period so that it can be easily worked, which manifests phase difference characteristics uniform over a wide wavelength band, and which can acquire a high transmittivity. The structural double-refraction quarter-wave plate is constituted such that a substrate (14) has the concavo-convex period structure of ?<SUB>min</SUB>/2 < P < ?<SUB>min</SUB> on its one face, when the shortest wavelength used is designated by ?<SUB>min</SUB>, such that the refractive index n<SUB>min</SUB> of the substrate in the wavelength ?<SUB>min</SUB> satisfies 1.5 < N<SUB>min</SUB> < 1.6, such that it has a high optical transmittivity, and such that the concavo-convex period structure satisfies the following formula: H = 3.5 x f - 5.65 x n<SUB>min</SUB> + 8.55 + a (-0.35 = a = +0.35), wherein P: the structural period of the concavo-convex period structure, H: the convex structure height [µm], L: the convex structure width, and f: a filing factor (= L/P).</p> |
