4 ms·

I'm really happy it was posted here, since I've never heard of this effect. Do you have some further reading on the "not useful or reliable" aspect? This site,

• blincoln 6y ago
  It's especially interesting to me because (as the article points out), it doesn't require any really exotic equipment or skills to build one. I'm a little surprised no one built one long before helium-neon lasers.