Light absorptive film provided with a reflection preventive means
AssigneeOlympus Optical Co., Ltd.
InventorsKimiaki Yamamoto, Takaharu Koike
Life of this patent
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Abstract
A light absorptive film comprising a light absorptive metallic layer and layer of dielectric material arranged on the incidence side of said light absorptive metallic layer, said light absorptive film being so adapted as to reduce reflection on said metallic layer by composing it in such a manner that the reflected wave produced at the boundary surface between said metallic layer and said layer of dielectric material is canceled by the reflected wave produced at the boundary surface of the other side of said metallic layer.
Claims6
A light absorptive film provided with reflection reduction means, said film comprising a light absorptive metallic layer and a layer of dielectric material arranged on the incidence side of said light absorptive layer, wherein the refractive index and thickness of said metallic layer and the refractive index and thickness of said dielectric material layer is selected in such a manner that the reflected wave produced on the boundary surface between said metallic layer and said layer of dielectric material is canceled by the reflected wave produced on the other surface of said metallic layer, said film satisfying the following condition,
- .vertline.r.sub.0 .vertline.+.vertline.r.sub.2 .vertline..gtoreq..vertline.r.sub.1 .vertline.,
- wherein r.sub.0 =.vertline.r.sub.0 .vertline.e.sup.i.theta. 0 represents reflectance on the surface of said dielectric material arranged on the incidence side, r.sub.1 =.vertline.r.sub.1 .vertline.e.sup.i.theta. 1 designates reflectance on the boundary surface between said layer of the dielectric material and said metallic layer, and r.sub.2 =.vertline.r.sub.2 .vertline.e.sup.i.theta. 2 denotes reflectance on the emerging side surface of said metallic layer and wherein the conditions mentioned below are satisfied:
- ##EQU4##
A light absorptive film provided with a reflection reduction means having the following composition:
- ______________________________________ Glass plate n.sub.0 = 1.52 First layer n.sub.1 = 2.33 d.sub.1 = 30 m.mu. Second layer n.sub.2 = 1.97-2.1i d.sub.2 = 20.3 m.mu. Third layer n.sub.3 = 1.33 d.sub.3 = 90.2 m.mu. Fourth layer n.sub.4 = 2.33 d.sub.4 = 21.5 m.mu. Fifth layer n.sub.5 = 1.97-2.1i d.sub.5 = 10 m.mu. Sixth layer n.sub.6 = 1.33 d.sub.6 = 624 m.mu. Glass plate n.sub.7 = 1.52 ______________________________________
- wherein n.sub.0 through n.sub.7 represent refractive indices of said glass plates and individual layers, and d.sub.1 through d.sub.6 designate the thicknesses of the individual layers.
Dependencies are inferred from the claim text.