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    Re: How does the AstraIIIb split mirror work?
    From: Bill Noyce
    Date: 2004 Apr 23, 10:29 -0400

    Fred Hebard wrote:
    > There would be a shift in position of the object if it were
    > reflecting off the unsilvered front of the mirror in one half
    > of the image and off the silvered back in the other half.
    Only if the object is very nearby, or if the front & back faces
    of the mirror aren't parallel to each other.
    Assuming the faces are parallel, the angular displacement would
    only be the parallax from shifting position of the reflecting
    point by a fraction of an inch.  For anything more than a few
    feet away, this is unnoticeable.  And besides, the back of the
    plain glass provides some reflection too, as does the front glass
    of the rear-silvered mirror.
    > Occasionally, I do see that, but most of the time, only the
    > single image is apparent.

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