| 摘要 |
PURPOSE:To obtain an antireflection film having sufficient reflection suppressing effect according to the refractive indexes of a substrate glass by forming the antireflection film to be coated on the surface of optical glass with respective specific components having specific refractive indexes and optical film thicknesses in each of four layers. CONSTITUTION:In providing the antireflection film C of the 4-layer structure of the Ist-IVth layers from the air A side according to substrate glass B having refractive indexes within the range of 1.42-1.9 refractive indexes, the expressions shown in the drawing column are satisfied, where the refractive indexes of the materials of the Ist-IVth layers are defined as N1-N4, respectively, the optical film thicknesses of the respective layers as N1d1-N4d4 and the design wavelength is defined as lambda0. Either of MgF2 or SiO2 is used for the Ist layer, any of ZrO2, TiO2, CeO2 or mixture of ZrO2 and TiO2 for the IInd and IVth layers and any of Al2O3, CeF3, or MgO for the IIIrd layer. In this way, stable optical characteristics of superior abrasion resistance and moisture resistance are obtained. |
