GLASS MATERIAL HAVING DISTRIBUTED INDEX OF REFRACTION AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a glass material of a uniform chemical composition having distributed indices of refraction on its surface. SOLUTION: The method for manufacturing the glass material having the distributed indices of refraction partially on its surface is characterized in that the glass materials, the density of which is varied by heating, is partially heated on its surface till below the temperature of generating concentration variation, and after cooling this heated part, again heated to a higher temperature than before time, repeating this process till the temperature of heated part reaches over the temperature of generating concentration variation by partially heating.