Patent ID: 7482296

Claim:
Alkali-containing aluminoborosilicate glass for the production of optical components with refractive index gradients which are produced through ion exchange of monovalent metal ions in a base glass of the following composition: 20≦SiO 2 ≦50 mole % 10≦B 2 O 3 ≦20 mole % 10≦Al 2 O 3 ≦35 mole % 10≦M 2 O≦34 mole % (M=Li, Na, K, Rb), wherein a molar ratio of 1 < Al 2 ⁢ O 3 M 2 ⁢ O < 1.3 is adjusted in order to reduce the tendency of the base glass toward crystallization for subsequent thermal treatment processes.