Any examples of naturally occurring holograms?

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  • Thread starter Mr Green T
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holograms, light, illusions, nature
Just downloaded a very interesting trail camera video that appears to contain a holographic red dome on the ground. Highest probability it's internal to the lenses and some reflection. It caused me to do a bit of fruitless searching on the topic of naturally occurring holograms. Do naturally occurring holograms exist?
 

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  • #2
berkeman
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How are you defining a hologram? What in the trail camera pictures reminded you of holography? I'm not aware of too many naturally occurring monochromatic light sources and interfernce within the coherence length...

https://en.wikipedia.org/wiki/Holography
 
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tech99
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I believe the colour on the wings of butterflies is caused by interference and so may be classed as a hologram.
 
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Mr. Green T has it. Butterfly wing colors, as well as those colored rings on oil-covered water and the color of peacock feathers, are all the result of constructive structured interference. This is mathematically identical to a hologram, creating a "false color" in white light, although not generating the displacement optical illusion we usually think of.

IIRC, some starfish have periodic structures that are actually holographic lenses, which would be an example of the more typical holographic usage. These are not the well-known eyespots on the tips of the arms, but scattered along the "skin".
 
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sophiecentaur
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I'm not aware of too many naturally occurring monochromatic light sources and interfernce within the coherence length.

I believe the colour on the wings of butterflies is caused by interference and so may be classed as a hologram.
I think it's only a matter of degree but that may be crucial for the definition of 'hologram' to apply. The bands of colour you see in a thin film have very low spatial frequency across the film and only require low coherence of the illumination (only the order of the thickness of the film).

OTOH, holograms that are created optically do not need high coherence of the light that they are viewed by. However, I seem to remember being shown hologram slides in the 60s which were only visible with laser light (in the laser lab at Uni).

Evolution is great though; it often (/always?) produces structures (variation of the hard chitin that insects are built of) in a way that 'designers' never would. It works by positive reinforcement of a design that gives a good result. (Hmm; a bit like some of my attempts at electronics along the lines of a blind watchmaker)
 

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