| 摘要 |
PURPOSE:To permit a position of a focal point to be changed auxiliary to cause a lot of men to able to use easily by making a sheet with an aluminium layer formed on the surface of a linear Fresnel lens bend properly to a direction perpendicular to the lens surface. CONSTITUTION:On the side of the lens surface of a linear Fresnel lens 3, an aluminum layer 2 is formed by laminating an aluminium foil or by evaporating aluminium. This screen is bent to the curved surface having a radius of curvature R larger than that of the lens 3. In order to make such a screen, the material is molded well in such a way that a lens material 7 and an aluminum foil 8 made of a resin composition are passed together between a metallic mold roll 4 and a forced roll 5 and the lens material and the aluminum foil are made to form a body. |
