Procedure for manufacturing ophthalmic bifocal lenses by ion exchange.

摘要

Procedure for manufacturing ophthalmic bifocal lenses by ion exchange in suitable glass substrates. The normal complex techniques of manufacturing bifocal lenses require a large number of steps, great precision and care in the industrial production process. The manufacturing procedure is characterized by three steps: creation (optional) of concave seatings in glass substrates of index n; ion exchange (thermal or assisted by electrical field) in the said glass, producing equal-index surfaces with a radius of curvature R and a maximum index value equal to n'; finally, surface cutting that removes the exchanged region in a certain area of the substrate, preserving it in the rest. The addition power obtained is: (n'-n)/R. The highly reproducible and easily automated manufacturing process is applicable in the ophthalmic industry. <IMAGE>