Re: [Phys-l] Sun's image due to reflecton by not a pinhole.

[Bernard Cleyet <bernardcleyet@redshift.com>]

Not necessary to think.  I found the reference** (same as the  
reference in Ditchburn  -- discussion for the problem of optimum pin  
hole diameter).  I had used a subjective criterion wherein the  
confusion was a fraction of the image height.   Mr Strutt used the  
criterion of the minimum focal length necessary to equal the hole  
replaced by a perfect lens.   Instead of using his Airy criterion, he  
used the fact that less than (1/4) wave length phase difference  
(center to edge) does not appreciable improve the definition.  This +  
Pythagorus does it.

** collected works V. 1  p. 513  (Phil. Mag. XI  p. 214)

bc had first tried the 1.22 Airy criterion and gave up.

p.s. as another poster (chuck britton?) proposed, it's images formed  
without reflection (non-plane) or refraction.






On 2009, May 01, , at 00:53, Bernard Cleyet wrote:

> OK?
>
> except I got ~ 7.5km or 5 miles  must do more thinking.
>
> The angular resolution (10 cm aperture) is about 7 microradian (1.4")
>
> On 2009, Apr 30, , at 13:49, Gary Karshner wrote:
>
> > Bernard,
> >          This reminds me of one of my favorite papers, in which Lord
> > Rayleigh calculated the focal length of a pinhole that had the
> > resolution
> > of a four inch telescope. It is something like 150 miles.
>
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