2 ms·
There are specialty processes and materials, but even multi-focal lenses are fully automated production. Stamping out and polishing cheap polycarbonate was alre
by theatrus2 10y ago
There are specialty processes and materials, but even multi-focal lenses are fully automated production. Stamping out and polishing cheap polycarbonate was already a razor thin margin at the lab end.
- mrob 10y agoPolycarbonate isn't a common material for glasses. It's very soft, so it needs an anti-scratch coating, and it has high dispersion so the chromatic aberration is very bad. It's only really good for safety glasses where the high impact resistance is important. Most cheap glasses are made from allyl diglycol carbonate (eg. CR-39) which has the best optical properties of any material commonly used for glasses.