High optical quality glass tubing and method of making

Abstract

A laminated or single layer glass cylinder and its method of making are disclosed. The laminated cylinder glass is a precursor component to enable making subsequent drawn tubing having high optical quality. The laminated cylinder glass may comprise a first layer of glass as a clad glass and a second layer of glass as a core glass. The second layer of glass may be bound to the first layer of glass. The second layer may have a higher CTE from about 5×10−7/° C. to about 100×10−7/° C. than the first layer of glass. The first layer and second layer of glass may have different softening points within about 200° C. of each other. In some embodiments, the first layer and second layer of glass may have different softening points from about 50° C. to about 200° C. of each other.

What is claimed is: 
     
         1 . A laminated cylindrical glass, comprising:
 a first layer of glass as a clad glass; and   a second layer of glass as a core glass bound to the first layer of glass, wherein the second layer has a higher CTE than the first layer of glass with a CTE difference from about 5×10 −7 /° C. to about 100×10 −7 /° C., wherein the first layer and the second layer of glass have different compositions and softening points within about 200° C. of each other.   
     
     
         2 . The laminated cylindrical glass of  claim 1 , further comprising a third layer of glass bound to the second layer of glass, wherein the third layer has lower CTE than the second layer of glass. 
     
     
         3 . The laminated cylindrical glass of  claim 2 , wherein the third layer of glass has a different composition than the second layer and the same or different composition as the first layer of glass, and wherein the glass composition of the second and third glass have different coefficients of thermal expansion. 
     
     
         4 . The laminated cylindrical glass of  claim 1 , wherein the CTE difference between the first layer and the second layer of glass is from 5×10 −7 /° C. to about 50×10 −7 /° C., or wherein the first layer and the second layer of glass have different softening points from about 50° C. of each other to about 100° C. of each other. 
     
     
         5 . The laminated cylindrical glass of  claim 1 , wherein the first layer and the second layer of glass have different softening points within about 50° C. of each other.