3 ms·

Depends on what you mean by perfect. its very precise, but I'm sure if you examined the surface with an electron microscope you'd still see imperfections. Edit

Depends on what you mean by perfect. its very precise, but I'm sure if you examined the surface with an electron microscope you'd still see imperfections. Edit: was incorrect about what I said below. Leaving it for posterity It's important to remember that the final surface - the one that actually reflects photons - is created chemically by releasing a gas inside a vacuum that very evenly coats the surface with reflective metal atoms. I'd wager that process fills in the ~last nanometers~ or so of imperfections. Or at least averages them out enough to not affect the optical performance.

Florin_Andrei 10y ago
No, it's not needed. Nanometers don't matter, that's the atomic level, far below what visible light could resolve. The metallic coating doesn't change the shape. Once you're below 20 nanometers it basically doesn't matter. The wavelength of visible light is on the order of 400 nanometers. In a different universe where the wavelength of visible light would be comparable to, or smaller than, the size of atoms, it would be very hard to make mirrors. Source: I make telescope mirrors.
- digler999 10y ago
  Thanks, I corrected my response. Was I partially correct about the gaseous reflective coating helping to smooth over any micro-imperfections?
- Avshalom 10y ago
  And indeed x-ray mirrors are a bitch (Although that's more because of destructive self interference than imperfections)
jakobegger 10y ago
You don't even need nanometer precision, since light has a wavelength of a few hundred nanometers. Random imperfections on a nanometer scale will be literally invisible.