WHY we don't see daily ARAGO/Poisson spot?

Question

I've been reading some stuff about Poisson spot , it's pretty interesting , but I don't understand what are the conditions for watching it, the arrange has to be long?, is spacial incoherence of light necessary?..pls help me,
no links pls, I would like to have an understandable explanation; thanks :)

I don't want to do it myself ( I'm to lazy for that I prefer just reading about it :P) I was asking about what are the mainly condition, how come we don't see it day by day?...
Epidavros, I've read the American Journal of Physics and they are two, even 3 papers talking about the experiments that this people themselves made it , and there is a whole theory behind it (wich I don't understand , by the way :) by Sommerfield and Weaver , so it truly had been seen and is I don't think it may had been an ¨invention¨ of Fresnel either.

Answer 1

Yes, you need a carefully set up arrangement with coherent monchromatic light to see it clearly.

Absurdly, the Poisson spot was named because Poisson said it was plainly absurd and could not occur. He claimed this predictions of Fresnel's theory of light basically proved Fresnel completely wrong. But it was Poisson who was wrong. Yet Poisson who was remembered.

There is a lesson there. Just not a good one.

Answer 2

I've never set up the demo myself (I should) but I saw it done once with just a cheap laser (and a lens to spread out the beam) and a steel ball hanging from a thread casting its shadow on the wall. The bright spot in the center of the shadow was obvious.

Why don't you try it with a pen laser and a cheapo lens and some sort of round ball yourself? Let us know what happens ... (I'll give it a shot, too.)