| 摘要 |
<p>1528437 Moulded glass articles having optical quality surface CORNING GLASS WORKS 20 May 1977 [25 May 1976] 21293/77 Heading C1M A method of making an optical glass article comprises (A) preparing a base anhydrous glass comprising, in mole per cent on an oxide basis, 70-82% SiO 2 , 10-17% Na 2 O and/or K 2 0 and 5-15% ZnO and/or PbO; (B) hydrating the base glass to a water content of at least 10% by weight; (C) partially dehydrating the glass to a water content of 3-8% by weight at a temperature above the softening point of the glass and, using an inert gas, e.g. nitrogen, at a total pressure above the vapour pressure of the water within the glass; and (D) moulding a preformed sample of the partially dehydrated glass against a die, the moulding portion of which is such that over a distance of at least 0À1 inch, on an arithmetic average basis, the roughness height is less than 3À0 microinches, under conditions sufficient to impart to a surface of the glass the surface figure of the die, the moulding being carried out under conditions sufficient to maintain the water content in the glass and to maintain or result in an optical quality surface on that portion of the glass surface to which the surface figure of the die is transferred. The process may be used to produce lenses, reflectors and similar optical elements.</p> |
