Re: [ATM] Favorite Spider Designs

[Michael Wheatley <mwheatley@telus.net>]

I had thought that the spikes around stars, diffraction or otherwise, 
were caused simply by diffraction around the edges of the spider so 
that a wire spider with several times as many edges would move more 
light into the spikes.

I have since read Texereau's reference to a stable layer of air 
heated or cooled by conduction along the surface of spider vanes that 
throws light into the spikes by refraction.  I expect this is why the 
lack of surface would give the wire spiders an advantage.

Can anyone say off hand what the relative importance is of edges 
(diffraction) and surfaces (refraction)?  Do we also have to consider 
reflection, diffuse and specular, from the vanes?

I expect the diffraction would be relatively predictable while the 
refraction would depend on temperature differences and the reflection 
would depend on ambient light and surface treatment.  I can see why 
the wire spiders may be best overall.

Mike Wheatley

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