FLAT PLATE OPTICAL ELEMENT AND ITS PRODUCTION

摘要

PURPOSE:To prevent the deformation, such as warpage, by forming an ion diffused layer having a uniform thickness over the entire substrate surface on the side opposite to an optical element forming surface and nearly equaling the total volume of the element part and the total volume of the ion diffused layer on the rear surface side. CONSTITUTION:Many lens parts 2 parted from each other are arranged on one surface side of the transparent glass substrate 1 having parallel flat surfaces on both surfaces and the diffused layer 3 having the uniform thickness is formed over the entire substrate surface by the diffusion of the same ions as the ions used for the formation of the lens parts 2. The total volume of the lens parts 2... is equaled nearly to the total volume of the diffused layer 3 having uniform thickness. The sum of the ion diffused regions 2 and the volume of the layer 3 on both surfaces of the substrate are equal in this way and, therefore, the quantity of the distortion arising from the ion diffusion is balanced between the both surfaces of the substrate. The generation of the warpage deformation of the substrate is thus substantially prevented.