Diffraction

Mahatma coat

Right I was watchina docco about a Museum in London that has thisbig glass roof, only tha pannels havethese little dots on them, for shade or some such, and anyway people jhave togo up to claen the bird **** off them regularly, so I thought why dont they put metal screensover them wit spaces tat are opposite the dots.

then I thought to meself what would happen if you put the screen just a little bit above the dots and just a little off centre, could you make a giant difraction grid, would it just bend the whitelight a bitor wouldyou be ableto getrainbow efects only on a huge scale, could you diffract different areas to difernt colours.

I've been thinkinabout this onefor ages, in My head it would work out to be reall cool, but 'Dreams != Reality, Dougal' as they say

anyone know what I'm ramblin on about, I'm not sure if I do!



that one I think, http://www.britishmuseum.org/the_museum.aspx

Professor_Fink

Mahatma coat wrote: »

then I thought to meself what would happen if you put the screen just a little bit above the dots and just a little off centre, could you make a giant difraction grid, would it just bend the whitelight a bitor wouldyou be ableto getrainbow efects only on a huge scale, could you diffract different areas to difernt colours.

I've been thinkinabout this onefor ages, in My head it would work out to be reall cool, but 'Dreams != Reality, Dougal' as they say

I'm afraid it wouldn't work. In order to get a decent diffraction pattern the gap needs to be close to the wave length of visible light (380-750 nm). 750 nanometers is still awefully small, and I suspect the dots on the roof are on a much larger scale.

Also, since the roof is curved, even if you could make each glass plate diffract, the different orientations would almost certainly end up averaging out the rainbow effect and giving you whit light.

Svenolsen

The windows clean themselves:

http://www.sciam.com/article.cfm?id=self-cleaning-materials

Mahatma coat

Thanks Frink.
so THAT Roof wouldnt work, is it still possible to do on a flatter surface, say, could I get a stickyon sheet ofd stuff for my Velux windows?

Professor_Fink

Well, there is an added complication in that the light should be coming from a point source. On sunny days, the sun should work ok, but when it is overcast, you'll be getting white light again.

Mahatma coat

Cool, I live in Brisbane, So Overcast isnot as much of an issue here. :D

thanks very much you have managed to answer all of my questions, some even before I realised they were questions