| 摘要 |
PURPOSE:To reflect incident light of an absorption region by an incident medium as well and to obtain high reflectivity by bringing multi-layered quarter wavelength films having an absorption region in a reflection to an incident medium side and the other multi-layered films to a substrate side at the time of forming the multi- layered quarter wavelength films having the different reflection bands into double structure. CONSTITUTION:15 Layers of the multi-layered quarter wavelength films 3 alternately laminated with titanium oxide layers 3a the optical thickness of which is a quarter of 3.44mum and silicon oxide layers 3b the optical thickness of which is likewise a quarter of 3.44mum are provided on a calcium fluoride substrate 1 having 3.5mm thickness at the time of forming a wide-band filter 2 on the substrate 1. 15 Layers of the multi-layered quarter wavelength films 4 alternately laminated with the titanium oxide layers 4a the optical thickness of which is a quarter of 4.56mum and the silicon oxide layers 4b the optical thickness of which is likewise a quarter of 4.56mum are then laminated on the lower side thereof via a silicon oxide layer 5 the optical thickness of which is a quarter of 4mum. The multi-layered films are formed into the double structure in the above-mentioned manner, in which the films 3 are positioned to the incident medium side and the films 4 to the substrate 1 side.
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