Re: Re[2]: ATM Airy disk frustrations

[Aplanatic@aol.com]

Dwight wrote:

<snip>
>  Now an infinite mirror, would have no edge. It would
>  produce an infinitely small disk or an impulse spot.
>  Well in reality, we should be able to measure the size
>  of the stars disk. Something like a f/.000000000001 mirror
>  would be interesting. <snip>

Stellar diameters have been measured by making the effective aperture large by
the use of two widely spaced auxiliary mirrors in a phase interferometer
configuration, similar to the two-slit Young interference experiment.  As I
recall (from memory) Michelson was the first to do this using the 100" Mount
Wilson scope with auxiliary mirrors some 5 meters apart.  He was able to
measure the approximate diameter of a few red giant stars in this manner in
the twenties.  Since then more sophisticated interference methods have been
employed but I no longer recall the details.  These initial efforts must have
been truly heroic in nature.

A wonderful, easily readable little book on the wave nature of matter and
light is Feynman's "QED, The strange Theory of Light and Matter."  I very
highly recommend it.  It is FUN, fascinating, and wholly accurate yet non-
mathematical.  After reading it one should understand the origin of the Airy
diffraction pattern.

Dave Rowe
Torrance, CA