Re: ATM Airy disk frustrations

[David McCarter <mccarterd@claven.fanshawec.on.ca>]

>Texereau's discussion starts with the diffraction disk and works back
>from that to a formula.  But I still haven't figured out exactly what
>causes the airy disk/difraction disk.

Light is a wave, with particle effects when light encounters solid stuff.
When perfectly parallel light, from a star, laser, or tiny pin hole at
great distance, is focused into a tight spot it won't add all together into
a very tight pile. The energy spills out. Imagine trying to pile dry sand
into a column ten inches high and one inch wide. Like trying to herd cats,
it's impossible.

I think it was Sir George Airy who first described why large telescopes did
not produce extremely small star points. Turns out that shorter wavelength
light, such as Ultra Violet or X-ray, does form smaller Airy spots, which
is why these wavelengths are used in micro-fabrication of integrated
circuits, or for very powerful microscopes.

Dave