Glass can be very stable at scale. But there are other materials proven to be stable at scale, cheaper than optically pure glass: concrete, ceramics, resins, some alloyed metals like chrome steel, chrome-moly steel, maybe exotics that are now common like carbon fiber in resin, known for its stiffness and rigidity.
I have also heard of laser arrays across the circumference of the face of the disc: each laser measures the distance to its receiver, thus providing real time feedback on the deformation of the lens at that time. Image minus deformation (minus atmospheric and other adjustments) = true image. That idea.
I’m trying still to understand the wisdom of 18 tons of pure silicon dioxide + 36 months of processing, compared to alternatives.
