| 摘要 |
A multi-layered antireflection film preventing reflection at two wavelength regions has a substrate of a refractive index nsub and a 5-layered structured formed on the substrate and composed of a first layer group including three layers of n1( lambda 1/4)-n2( lambda 2/2)-n3( lambda 1/4) and a second layer group including two layers of n4( lambda 1/4)-n5( lambda 1/4). The factors are determined such that the following conditions are met: 1<n1</=nsub, n2>/=nsub 1<n3</=nsub and nsub (n52/n42) &persp& 1 The layers of the first layer group are made of materials selected from dielectric materials exhibiting compression stresses, while the layers of the second group layer are made of materials selected from dielectric materials exhibiting tensile stresses.
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