PRODUCTION OF LENS HAVING AXIAL REFRACTIVE INDEX DISTRIBUTION

摘要

PURPOSE:To obtain the titled lens having remarkably decreased laminar fluctuation of the refractive index, excellent optical characteristics and large refractive index difference, by controlling the Sb2O3 concentration in a specific glass for lens. CONSTITUTION:A carrier gas accompanying a raw material gas for forming glass and containing SbCl5 or TiCl4 is supplied together with a combustible gas and a combustion-assistant gas to the torch 10 via the supply pipes 11, 12 to effect the flame hydrolysis of the raw material gas. The produced glass soot 13 composed mainly of SiO2 and containing a dopant (Sb2O3 or TiO2) for controlling the refractive index is deposited on the plane surface of the starting substrate 14 varying the concentration of Sb2O3 or TiO2 along the normal line of the plane to form a soot layer 15. The soot layer 15 is heated in an inert gas at a high temperature to form a plate glass 16 for lens having refractive index varying continuously along the direction of thikness. the objective lens 17 having axial refractive index distribution can be produced by the spherical working of at least one end face 17A of the glass taking the direction of the refractive index distribution as the axis.