#
#According to the NASA investigation of the Hubble mirror problem, there
#was nothing wrong with the specs. The backup mirror built to the same
#specs by Kodak is *perfect*. The problem was that Perkin-Elmer bollixed
#up the testing of the figure of the mirror and ignored the results of
#a Foucault test that showed the mirror to have spherical abberations
#because their primary test was supposed to give more accurate results.
#Unfortunately, they installed a fixture backwards when making the
#primary measurements and got the *wrong* result.

I'm pretty sure there was never a Foucault test; that
there hadn't been one became an issue after the mistake
was discovered. This was brought up at NASA reviews I
attended. After all, the interferometric test was supposed
to be so accurate that a crude test such as the Foucault
test wouldn't tell you anything you didn't already know
(or so they thought).

The "fixture" that was used backwards was the Invar rod;
It was indeed used backwards, but that was not the chief
reason for the mis-manufactured null corrector. This was,
as I posted earlier, the laser return from the end cap,
which had had a fleck of black paint scraped off.

Bill