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Re: [Telescopes] Re: Mirror Grinding -- Off axis

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  • Norman Higgs
    Just out of curiosity - who do you work for? Or is that classified? LOL ... From: hwnewton To: Sent:
    Message 1 of 9 , May 1, 2002
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      Just out of curiosity - who do you work for? Or is that classified? LOL
      ----- Original Message -----
      From: "hwnewton" <hal.newton@...>
      To: <telescopes@yahoogroups.com>
      Sent: Tuesday, April 30, 2002 8:49 PM
      Subject: [Telescopes] Re: Mirror Grinding -- Off axis


      > This is part of why I brought up the question... It's interesting
      > to me that where I work, we actually grind off axis mirrors (and
      > figure them) as off axis right from the start. Now since I'm not in
      > the otics department, I don't know just how all of this is done, and
      > I'm investigating there too, but I was curious about how others do
      > it. The trouble with comparing what is done at work and what is
      > done in ATM is that work makes rather exotic mirrors with zero CTE
      > and some really stiff materials. (CTE - Coefficient of thermal
      > expansion)
      >
      > - Hal
      >
      > --- In telescopes@y..., Norman Higgs <nfhiggs@p...> wrote:
      > > I would think that it would take a VERY experienced and skilled
      > optician to
      > > grind and polish an off-axis parabola. Its more efficient (time
      > wise) to cut
      > > them from a well figured, zone-free, large mirror - which also
      > requires a
      > > high degree of skill. This is one reason you don't see many larger
      > aperture
      > > off-axis parabolics. The largest one that DGM offers is 9". The
      > mirror
      > > supplier they use advertises off -axis parabolic mirrors up to
      > 16". I would
      > > imagine that a well-made 16" off-axis mirror has a horrendous
      > pricetag!
      > > ----- Original Message -----
      > > From: "hwnewton" <hal.newton@i...>
      > > To: <telescopes@y...>
      > > Sent: Monday, April 29, 2002 9:01 PM
      > > Subject: [Telescopes] Mirror Grinding -- Off axis
      > >
      > >
      > > > I've got too many questions tonight. I'll stop after this one.
      > > >
      > > > I'm told that off axis parabolas are normally ground as on axis,
      > and
      > > > then cut off axis (by amatures). Does anyone know how to grind
      > off
      > > > axis to begin with?
      > > >
      > > > -Hal
      > > >
      > > >
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