FORFARANDE FOR FRAMSTELLNING AV ETT GLASALSTER MED EN GRADERAD BRYTNINGSINDEXPROFIL MED NESTAN PARABOLISK FORM

摘要

A method of producing a glass article having a graded refractive index profile of a parabolic nature is disclosed. The method comprises soaking a preform having a porous matrix with interconnected pores into a stuffing solution containing at least one index modifying dopant of predetermined solubility in the stuffing solution for a time interval to fill the pores with the dopant solution, precipitating the dopant into the porous matrix approximately uniformly throughout, soaking the preform into a solvent solution having a solubility for the dopant lower than the solubility of the dopant in the stuffing solution for a time interval sufficient to cause substantially all of the dopant to redissolve and for diffusion to take place out of the porous matrix in such a way that the dopant concentration decreases as a function of radial distance from the central axis, precipitating the dopant in the porous matrix by reducing the temperature of the preform to a level such that the dopant is precipitated out of solution, removing the solvent and where necessary decomposition products from the preform, and heating to consolidate the preform to produce a glass article having a graded refractive index profile of the parabolic nature.