| 摘要 |
PURPOSE:To prevent the degradation in capacity of an antireflection film due to secular change by providing a surface protective film consisting of a dielectric thin film on the surface of the antireflection film. CONSTITUTION:This device consists of a GaAs substrate 1 as the base body, a ZrO2 thin film (nd=lambda/4)<2> as the antireflection film provided by vacuum deposition, and a single layer film 3 of an SiO2 thin film (nd=lambda/2) as the surface protective film provided on the surface of the ZrO2 thin film 2 by vacuum deposition. The surface protective film 3 prevents the antireflection film 2 from coming into direct contact with air to prevent the degradation of the antireflection film 2. Thus, an optical device of less secular change is obtained. |
