Sol-gel method for making gradient index optical elements

Claim 1

A method for making a gradient-index glass comprising: forming a mixture of a silicon alkoxide and an alcohol in a solution sufficiently acidic to partially hydrolyze the silicon alkoxide; adding to the mixture an index modifying metal alkoxide selected from the group consisting of alkoxides of titanium and zirconium; adding water to the mixture containing the index modifying metal alkoxide and the while agitating, to convert the metal alkoxides to a network of corresponding metal oxides suitable for gelation; molding the mixture containing the network of metal oxides for sufficient time to form a gel; acid leaching the molded gel for sufficient time to remove some of the index modifying metal oxide; fixing the gel in water or a mixture of water and alcohol; drying the fixed gel; and sintering the dried gel into a transparent gradient-index glass.

Claim 2

A method for making a gradient-index glass comprising: forming a mixture of a silicon alkoxide and an alcohol in a solution sufficiently acidic to partially hydrolyze the silicon alkoxide; adding to the mixture an index modifying metal alkoxide selected from the group consisting of alkoxides of titanium and zirconium; adding water to the mixture containing the index modifying metal alkoxide and the while agitating, to convert the metal alkoxides to a network of corresponding metal oxides suitable for gelation; molding the mixture containing the network of metal oxides for sufficient time to form a gel; acid leaching the molded gel for sufficient time to remove some of the index modifying metal oxide; fixing the gel in water or a mixture of water and alcohol; drying the fixed gel; and sintering the dried gel into a transparent gradient-index glass.

Claim 21

A method for making a gradient-index glass comprising: forming a mixture of a silicon alkoxide and an alcohol in a solution sufficiently acidic to partially hydrolyze the silicon alkoxide; adding to the mixture an index modifying metal alkoxide selected from the group consisting of alkoxides of titanium and zirconium and at least one additional metal alkoxide element selected from the group consisting of alkoxides of aluminum, boron, and germanium; adding water to the mixture containing the index modifying metal alkoxide and the at least one additional metal alkoxide element, while agitating, to convert the metal alkoxides to a network of corresponding metal oxides suitable for gelation; molding the mixture containing the network of metal oxides for sufficient time to form a gel; washing the molded gel with water; acid leaching the washed gel for sufficient time to remove some of the index modifying metal oxide, wherein said acid leaching is carried out in a bath comprising water and one or more acids selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid; fixing the gel in an aqueous solution of 20-40 volume % of an alcohol having 1 to 4 carbon atoms; drying the fixed gel; and sintering the dried gel into a transparent gradient-index glass containing 60 to 98 mole % silicon oxide, 0.1 to 25 mole % of corresponding index modifying oxide, and less 25 mole % of corresponding additional metal oxide element.

Claim 22

A method for making a gradient-index glass comprising: forming a mixture of a silicon alkoxide and an alcohol in a solution sufficiently acidic to partially hydrolyze the silicon alkoxide; adding to the mixture an index modifying metal alkoxide selected from the group consisting of alkoxides of titanium and zirconium and at least one additional metal alkoxide element selected from the group consisting of alkoxides of aluminum, boron, and germanium; adding water to the mixture containing the index modifying metal alkoxide and the at least one additional metal alkoxide element, while agitating, to convert the metal alkoxides to a network of corresponding metal oxides suitable for gelation; molding the mixture containing the network of metal oxides for sufficient time to form a gel; washing the molded gel with water; acid leaching the washed gel for sufficient time to remove some of the index modifying metal oxide, wherein said acid leaching is carried out in a bath comprising water and one or more acids selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid; fixing the gel in an aqueous solution of 20-40 volume % of an alcohol having 1 to 4 carbon atoms; drying the fixed gel; and sintering the dried gel into a transparent gradient-index glass containing 60 to 98 mole % silicon oxide, 0.1 to 25 mole % of corresponding index modifying oxide, and less 25 mole % of corresponding additional metal oxide element.