PURPOSE: To remove a ripple owing to an SiO2 surface hardening layer and to obtain good reflection preventing characteristics, by providing a reflection preventing layer made of a metallic oxide at the boundary between the SiO2 surface hardening layer and a high refactive index resin.
CONSTITUTION: An SiO2 surface hardening layer 32 is provided on a high refractive index synthetic resin 30 having a larger refractive index than that of SiO2, and a reflection preventing layer having four-layered films consisting of layers 33, 34, 35 and 36 is disposed thereon. A layer 31a having 0.05λW0.15λ optical film thickness of SiO2 is provided to the resin 30 side in order to remove a ripple which is generated by reflectin at the boundary between the resin 30 and the layer 32 and by which reflection preventing characterstics are deteriorated, and thereon, a layer 31b having 0.01λW0.15λ optical film thickness of ZrO2, HfO2, Ti2O3, TiO2, Ta2O3, Si3N4, Yb2O3, Y2O3 and Al2O3 is stacked further.
KOJIMA KENJI
MOGAMI TAKAO
MATSUSHIMA KOGYO KK