MANUFACTURE OF GLASS ROD HAVING REFRACTIVE INDEX GRADIENT

摘要

PURPOSE:To produce a glass rod having adequate refractive index gradient, by unstuffing a stuffed porous glass rod with a dopant solution having low concentration, and precipitating the dopant in the pores. CONSTITUTION:A porous glass rod is stuffed with a dopant solution, and is unstuffed in a dopant solution containing the same kind of dopant as the above solution and having lower dopant concentration. The unstuffed rod is immersed in a solvent maintained at <=5 deg.C and having a dopant solubility of <=0.5g/100g (solvent) at 5 deg.C to effect the precipitation of the dopant in the pores. The glass is then dried and sintered to collapse the pores. The process gives a glass rod having almost ideal refractive index gradient and excellent axial aberration characteristics.