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Soap bubbles (1 Viewer)

Binastro

Well-known member
Why do soap bubbles seem to have the colours of multicoating?

Thin films, different thicknesses? But why the colours of fine multicoated optics?
 
Thanks for the link.

What I don't intuitively understand is that in multicoated optics, several layers contribute to the final colour, but with the soap film there is a single thickness. Presumably, the soap bubble is made up of one layer that changes in thickness over time producing different colours.

I suppose a single antireflection coating producing the colours of multicoating might not actually work properly.
 
Thanks for the link.

What I don't intuitively understand is that in multicoated optics, several layers contribute to the final colour, but with the soap film there is a single thickness. Presumably, the soap bubble is made up of one layer that changes in thickness over time producing different colours.

I suppose a single antireflection coating producing the colours of multicoating might not actually work properly.

Indeed, the different colours in the soap bubble are caused a non-uniform thickness and differing angles. With AR coatings you obviously want a uniform thickness of each layer.

Joachim
 
But can the distinct look of multicoating be mimiced by a single coating of the wrong thickness, which does not perform correctly, but deceives the buyer into thinking that the binocular is multicoated?
 
Petrol (gasoline) floating on water gives the same effect, presumably because different fractions of different densities arrange themselves in layers.

Lee
 
But can the distinct look of multicoating be mimicked by a single coating of the wrong thickness, which does not perform correctly, but deceives the buyer into thinking that the binocular is multicoated?

If you are able to see two different hues depending on angle you should be fine. In general you can obviously create a single coating in every colour you want, but if you come to the point where you apply your custom singlecoating to look like a multicoating, you could as well have another go and do the real thing.

For what it's worth, I used to own two pairs of soviet ZOMZ 7x50 which looked very much the same including the greenish objective lenses. But the older one is from 69 and is single coated and the later one is from 79 and multicoated. Both are great for the $40 I paid. I gave the later one to a friend.

Joachim
 
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