GB1367335A - Manufacture of glass lenses - Google Patents

Abstract

1367335 Lenses EASTMAN KODAK CO 25 Nov 1971 [27 Nov 1970 (2)] 54745/71 Heading C1M Lenses are manufactured by moulding glass 47 in moulds of glass-like carbon 15, 17, the mould being of high surface quality and accuracy, in an inert or non-oxidizing atmosphere. Preferably the mould and glass are preheated, the mould to 530-590‹ C. and the glass, an optical barium crown glass, is softened at 600-700‹ C. The atmosphere may consist of 95% N2 and 5% H2. A pressure of 200-300 lb. may be applied to the mould, for 2-20 seconds, to ensure accurate moulding. One embodiment (Fig. 1) comprises a fixed mould assembly 1 and a movable assembly 5, combined with plunger 7, contained in a glass envelope 13 in which atomspheric conditions can be controlled. The mould assemblies comprise glass-like carbon inserts 15 and 17, graphite cores 19 and 21 to support the inserts, supports 23 and 25, ceramic encased heaters 27 and 29 and thermocouple assemblies 31 and 33 which are thermally connected to the mould inserts to control moulding temperatures. The opposing surfaces of the mould inserts are contoured according to the shape of the lens to be produced, being finished to have a high surface accuracy and quality comparable to that of the intended lens so that grinding and polishing of the product lens should not be necessary. A further embodiment incorporates a vertical assembly with aligning guide pins (Fig. 3, not shown). The mould may comprise a ring-like element 129 (Fig. 5a) disposed around insert 127 for adding the necessary thickness to the lens to be produced.