Aspect of glass softening by master mold

Parabolic mirror segments are produced from flat glass plates, and the glass plates are softened to parabolic surface by master mold. In the softening of the glass, the closeness of fit between the glass and the master mold will vary according to the surface tension of the glass, and it will influence the precision of the softening process. This problem brings about the necessity of improving the precision of the process.