Transactions of the INDIAN CERAMIC SOCIETY Vol. 48 1989
Development of Photochromic Ophthalmic Glass
S. K. DAS, A. K. CHAUDHURI, N. BISWAS AND
S. THIAGARAJAN
Pages : 1-4
DOI : 10.1080/0371750X.1989.10822927
Abstract
Melting conditions of photochromic glasses of the ophthalmic variety
were investigated. Melting consisted of two parts, viz. a pyrex type
glass and then a photochromic composition with the premelted glass.
The method followed suppressed the loss of halides from the molten
glass by reducing the melting time. Alkali-halide-saturated air cover
over the melt surface was found necessary to make the glass photochromic.
Ophthalmic specifications were attained by replacing part
of the alkalis by PbO and BaO for matching index and Abbe values.
Absorption studies indicated the formation of AgCI1_x Brx type
crystallites with sizes ranging from 100 to 500 A during heat treatment
of the glass.
