| 摘要 |
PURPOSE:To obtain the antireflection film which is not only low in reflectivity but also not increases the reflectivity even at the time of a high incident angle and is small in the difference in the reflectivity between an S polarized light component and a P polarized light component by successively laminating a layer consisting of yttria or lanthania and a layer consisting of silica at specific film thicknesses and thereby forming the above-mentioned film. CONSTITUTION:The 1st layer consisting of the yttria or lanthania and the 2nd layer consisting of the silica are successively laminated and are so formed that the optical film thicknesses of the 1st layer and the 2nd layer have the values of n1 d1 and n2 d2, respectively within the range expressed by equation: 0.28lambda<n1 d1<0.30lambda and 0.25lambda<n2 d2<0.33lambda(where lambda is the wavelength of the light to be applied, n1, n2 are respectively the refractive indices of the 1st layer and the 2nd layer; d1, d2 are respectively the film thicknesses of the 1st layer and the 2nd layer). The antireflection film which is low in the reflectivity in spite of the large incident angle, is small in the difference in the reflectivity between the S polarized light component and the P polarized light component and is simple in constitution is obtd. in this way. |
