| 摘要 |
PURPOSE:To attain an antireflection effect which is excellent in a wide wavelength region from near IR light to visible light by specifying the components and optical film thicknesses of the respective layers of the antireflection coating. CONSTITUTION:TiO2 is deposited by evaporation on the 1st, 3rd, 5th, and 7th layers of the antireflection coating counted from a glass substrate side, SiO2 on the 2nd, 4th and 6th layers and MgF2 on the 8th layer. The optical film thicknesses ND (N is the refractive index of the thin films and D is the film thickness) are specified to (0.2 to 0.3)xlambda/4 for the 1st layer, (0.3 to 0.5)xlambda/4 for the 2nd layer, (0.7 to 0.8)xlambda/4 for the 3rd layer, (0.1 to 0.3)xlambda/4 for the 4th layer, (0.2 to 1.5)xlambda/4 for the 5th layer, (0.3 to 0.35)xlambda/4 for the 6th layer, (0.4 to 0.6)xlambda/4 for the 7th layer, (1.3 to 1.4)xlambda/4 for the 8th layer (lambda is a design wavelength). The reflectivity is lowered to <=0.2% in the case of IR light and to <=0.8% in the case of visible light. |
