FLUORIDE GLASS ROD LENS, ITS PRODUCTION AND APPARATUS THEREFOR

摘要

PURPOSE:To obtain the subject lens having graded index-type convergent refractive index distribution by introducing specific raw material gas and fluroine- containing gas into a reaction vessel containing a fluoride glass fiber, depositing fluoride glass powder on the fiber and making the powder transparent. CONSTITUTION:A fluoride glass fiber 1 held with a chuck 2 is set in a reaction vessel 3 and reciprocated on a rail 6 under rotation around the axis with a holding table 5. A raw material gas containing at least one kind of organic metal compound gas is introduced as a raw material gas for a fluoride glass into the reaction vessel 3 through the core tube of a double-walled feeding pipe 10 while varying the feeding rate with time and a fluorine-containing gas is introduced into the reaction vessel through the outer tube of the double-walled tube 10. The introduced gases are made to react with each other and the formed fluoride glass powder is deposited on the fiber 1 to obtain a porous material of a fluoride glass. The porous material is made transparent by heating at 250-300 deg.C to obtain a fluoride glass rod lens having compositional ratio varying from the center toward the circumference and having a refractive index distribution decreasing toward the circumference.