3 ms·
The difference is size, the simple grinding process does not keep accuracy for big mirrors and lenses.
by AstralStorm 7y ago
The difference is size, the simple grinding process does not keep accuracy for big mirrors and lenses.
- kragen 7y agoThe accuracy isn't in the process of grinding; it's in the process of measurement. All the grinding process needs to do is to remove only a small amount of material, which is itself a nontrivial problem; a single large grain of grit can ruin weeks or months of work, so amateur astronomers may get very angry at you for things that seem unreasonably minor, like opening a door without washing your hands. But that's not a problem that scales superlinearly with mirror size. Really large mirrors are segmented anyway.