Abstract:
Ophthalmic lenses with locally variable indices of refraction produced from microporous glass bodies diffused with inorganic salts and rendered transparent by heat treatment. Local variations in refractive index result from differences in concentrations of the salts produced by controlled diffusion and/or selective leaching after impregnation of the porous bodies.
Abstract:
Nondestructive marking of plastic artificial intraocular lenses for coding purposes. Exposure with ultraviolet radiation of portions of a lens surface forming boundaries of desired coding characters or similar exposure only of areas forming the characters themselves produces a differential in refractive index of the material of the lens wherewith detection and reading of the coding may be accomplished before and/or after intraocular implantation.
Abstract:
Ophthalmic lenses formed of ophthalmic glass and having accurately finished front and back curved surfaces and edged to the shapes desired are heated in molten salt bath and ion-exchange hardened on all surfaces thereof so as to satisfy high safety standards while being substantially free from optical image distortions for objects viewed therethrough. The invention includes method and apparatus for rapid and controlled pre-heating, soaking and cooling steps of lenses relatively cheaply and in sizable numbers at the same time.
Abstract:
There is disclosed an ion exchange-strengthened ophthalmic segment glass suitable for the fabrication of fused bifocal and trifocal ophthalmic lenses. More particularly, there is disclosed a lanthanum-silicate based ophthalmic segment glass having indices of refraction of about 1.57 to about 1.65 which is suitable for chemical ion exchange strengthening so as to develop a compressively-stressed ion-exchanged surface layer having a depth of at least 60 micrometers.
Abstract:
Chemically stable, semiconducting glasses having a resistivity of from about 2 .times. 10.sup.7 to about 6 .times. 10.sup.8 ohm.sup.. cm contain 25 to 35 weight percent of vanadium pentoxide, 10 to 20 weight percent phosphorous pentoxide, and from 35 to 45 weight percent of molybdenum trioxide. These semiconducting glasses are melted readily, are castable into desired shapes, and offer good resistance to devitrification.