Abstract

To date, most methods of fabricating 1 meter and greater lightweight glass substrates have required extensive labor to achieve the thin ribs necessary for full thickness, low density blanks.¹ In this paper progress on the Gas-Fusion_tm process tpwards lighter and larger blanks is discussed. Full thickness blanks of 80%-90% lightweighting are discussed. Originally funded by NASA and Discussed in several paper presentations, ^2,3 continued research has been internally at Hextek, with additional funds from Ball Aerospace Systems Division. Ribs as thin as 1mm have been achieved in 30cm blanks, producing core densities as low as 6%. The process involves fusing cut tubing between two plates of the same glass by heating in the furnace. At the appropriate temperature the glass is soft enough to achieve a complete welding of the contacting surfaces, eliminating the need for frit bonding required of lower temperature bonding procedures. The Temperature is raised further and a pressurizing gas is distributed among the now sealed tubes. Complete expansion of the tubes produces straight walled fibs with large.fillets and contact surfaces between the ribs and the faceplates. One meter blanks made with the Gas-Fusion^ process require less than two weeks to produce.

© 1987 Optical Society of America