Patent ID: 7069747

Claim:
A method for constructing a mirror blank assembly, comprising the steps of: a) arranging hollow, sealed glass balls, on a front face sheet, and in close proximity to each other to permit fusing upon expansion, the hollow, sealed glass balls having a fixed, initial internal pressure; b) restricting the expansion of the glass balls with a bounding structure during expansion of the glass balls to force the glass balls into a densely packed array of cells; c) applying heat to soften the glass balls and increase pressure within the glass balls as the glass balls fuse with each other during expansion, forming cells, wherein as a result of fusing, the glass balls contact the front face sheet as a result of the increased pressure within the glass balls; d) annealing and cooling the mirror blank assembly to below annealing temperature associated with the glass balls; e) venting the cells to equalize internal and external pressure applied to the front face sheet; and f) keeping the cells vented in the mirror blank assembly.