ORIGINAL PLATE FOR MOSAIC FRESNEL LENS* PRODUCTION OF SAID DUPLICATE PLATE AS WELL AS SAID ORIGINAL PLATE AND DUPLICATE PLATE AND SYNTHETIC FRESNEL LENS ORIGINAL PLATE AND COMPOSITE FRESNEL LENS

摘要

PURPOSE:To obtain a composite Fresnel lens of a large size by making multiple grooves of arcs of concentric circles corresponding to the grooves of the Fresnel lens, using this as an original plate for a mosaic Fresnel lens and obtaining the circulate duplicate plate of said original disc. CONSTITUTION:A multiplicity of grooves of arcs of concentric circles such as the ones corresponding to the grooves of the Fresnel lens are made from the center P of the longer side of a rectangle A for original plate. With this as an original plate, two sheets of duplicate plates are made and these are combined by a suitable method such as high-frequency welding. With this constitution, one set consisting of two pieces of Fresnel lenses are combined, by which a composite lens twice larger than the rectangle A is obained. Multiple grooves of arcs of concentric circles corresponding to the grooves of the Fresnel lens are made from the vertex Q of B of a rectangle BB' for the original plate of the same size. In this case, the grooves of opposite phases should be made from the vertex Q' of B'. These make it possible to obtain the composite lens of 4 times larger than the rectangle B.