METHOD FOR FORMING GLASS OPTICAL ELEMENT

摘要

PURPOSE:To obtain a forming glass material of nearly a spherical shape at a low temperature in a short time by placing a glass material cut or machined to a prescribed volume on a pan made of carbon and thermally softening the glass material into a prescribed shape in a decompressed inert gas atmosphere. CONSTITUTION:A cylindrical glass material 1 cut or machined so that the outside diameter (phi1) and a height (h) may provide a prescribed volume is placed on a pan 2 made of carbon and closed with a cover 3 made of carbon. The covered pan is then placed on a carrier pedestal 5 made of quartz glass and thermally softened with infrared rays at 3-50mum wavelength emitted from a halogen lamp 6 in an inert gas atmosphere decompressed to 20-50 Torr to afford a glass material 4 having a smaller curvature radius of both the first and second surfaces than that of the formed optical element and the curvature radius (R1) of the first surface and the curvature radius (R2) of the second surface in the relation of 2R1