Great Claude, it looks nice.
The spot size itself seems to be based on two things:
1. the resolving power of our eyes, according to
http://www.wikilectures.eu/index.php/Resolution_of_human_eye we can resolve about 100 microns at screen distance.
2. the spatial coherence of the incident light (how similar is the light wave laterally), according to
https://www.photonics.ethz.ch/fileadmin/user_upload/pdf/Papers/divitt15a.pdf the coherence is about 7 to 80 times the wavelength of sunlight for overcast and clear sky respectively. So 3.5 to 40 microns.
Since the second one is smaller, the light coherence seems to the one that matters, and affects the interference width. Either way the spot size doesn't make much difference to the colour unless it is really foggy (e.g. coherence width less than 7 times wavelength of light), then becomes less colourful.
Here are some more:
February 18, 2007, 02:01:14 AM
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