Fluoroborosilicate glass and clad article.

摘要

There are disclosed fluoroborosilicate glasses that are particularly adapted to being drawn with lead silicate core glasses to produce clad glass fibers useful in forming fiber optic bundles to be incorporated in night vision equipment. The cladding glass has a refractive index not over about 1.45 and a coefficient of thermal expansion not over about 120 x 10<-><7>/ DEG C. The clad fiber has a numerical aperture of at least one.