5 ms·
That's huge. Everyday profile accuracy can be spoken of in "quarter wavelength"-like terms.
by a9h74j 5y ago
That's huge. Everyday profile accuracy can be spoken of in "quarter wavelength"-like terms.
- xxpor 5y agoWas that true in 1979?
- HPsquared 5y agoAccuracy less than a wavelength has been possible for a long time: https://en.wikipedia.org/wiki/Foucault_knife-edge_test https://en.wikipedia.org/wiki/Foucault_knife-edge_test
- xxpor 5y agoHuh wow, that's brilliant! I was expecting something super complicated with extremely high tech sensors.
- a9h74j 5y agoSpherical-against-spherical and flat-against-flat grinding can be self-truing, so in effect centuries-old clever results required clever testing to verify. High tech in those days? Rumor I heard in the mid-1980s was that LLNL had [vertical?] lathes which could mechanically cut mirrors to optical-profile accuracy. Supposedly 100gpm liquid flows were required to keep the part temperatures uniform.