| 摘要 |
PURPOSE:To obtain an optical element, such as lens or prism, satisfying optical requirements by removing the surface defects of a glass material in advance and pressure molding between molds high in face precision. CONSTITUTION:The glass material is preliminarily molded by grinding, etc. to remove surface defects, and surface roughness is finished to about <=1/10m. This material is placed on a lower mold 4 in a tightly enclosed chamber 1 and an upper mold 3 is set. A cover 2 is closed, water is allowed to flow through a cooling water pipe 20 and a heater 8 is energized. The inside of the chamber 1 is evacuated to a prescribed vacuum, and then, a valve 16 is opened to introduce an inert gas. When the glass is heated to or above the softening point, an air cylinder 10 is actuated to mold the glass with pressure. This method prevents trouble where the air on the surface of the material is unable to escape by the presence of the large roughness of the surface during the pressure molding and exerts adverse effects on the surface of the optical element. As a result, an optically satisfactory optical element can be obtained. |
