Patent ID: 6157405
Filing Date: 2000-12-05
Classification: G02B,H04N

Abstract:
An apex-angle variable prism comprising:a plano-concave lens and a plano-convex lens, each having opposed flat and spherical surfaces and whose spherical surfaces are confronted to each other and have identical radius of curvatures; andmeans for rotating along a rotational center line at least one of said plano-concave lens and said plano-convex lens relative to the other lens along the spherical surfaces to vary the apex angle which is formed by said plano-concave lens and said plano-convex lens, wherein said apex angle varying means include a rotational fulcrum position which is disposed at one end side of said one lens, and a rotational driving portion which is disposed at the other end side of said one lens, and wherein said one end side and the other end side of said one lens are supported respectively by said rotational fulcrum portion and said rotational driving portion, said rotatable fulcrum portion being in the form of a pivot bearing which is disposed at a point on the rotational center line which is inclined to the normal direction of the flat surface of said one lens by a predetermined angle and passes through the radius of curvature of the spherical surface of said one lens.