Mechanism behind the generation of tiny bright spots

[johnthekid]

TL;DR

Mechanism behind the generation of tiny bright spots in night vision devices and slit experiments

Watch these clips


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The flickering bright spots in the second clip which is a night vision device, are the mechanism behind how those bright spots are generated in the night vision device the same as how the individual photon spots are generated for the slit experiment in the first clip?

 

[Ibix]

Sort of. I don't think the image intensifier is sensitive enough to detect individual photons, but it's sensitive to small numbers of them. Their arrival is random. The average arrival rate at a pixel is the image brightness there, but when you're talking about small numbers of photons the random fluctuations in the arrival rate are large enough to be visible as occasional bright and dark spots. The technical term is shot noise.

So the ultimate source of the spots is the quantised nature of light in both cases, but in the Young's slits experiment it is a very dim source so individual photons are counted after diffraction, while the speckle in the image intensifier is a much brighter source that is still dim enough for arrival time statistics to matter.