What’s the difference between pigments and light scattering structures?

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I saw a similar question being asked here but I understood absolutely none of the responses so I’m gonna ask for myself.

I often hear people saying that only brown and orange pigments exist, and all other colors are caused by light bouncing/scattering off certain microscopic structures and then hitting our eyes.

What I don’t understand is how brown and orange can exist without being scattered light??

Like- “brown animals are brown because they have brown pigments, blue animals are blue because that’s the color their coat bounces back at you”

WHAT’S THE DIFFERENCE.

I’m sorry if I’m not explaining myself well.

In: Physics

3 Answers

Anonymous 0 Comments

> pigments and light scattering structures

Different physical processes are at work here.

Pigments *absorb* certain colors/wavelengths (converting that part of the spectrum to heat) and reflect other parts. Thus a green pigment, for example, will absorb blue and red light and appear, well, green. The same goes for dyes, as in a glass of red wine.

But some colorless substances can also filter out colors if they are given a *regular* microscopic structure, roughly of the size of light wavelengths. The simplest example is a CD, where you can see rainbow colors albeit the object itself is just colorless metal on a plastic support. This is caused by its regularly spaced grooves, which happen to be of the right size. (See the [Diffraction grating](https://en.wikipedia.org/wiki/Diffraction_grating) Wiki page for the physics.)

This also exists in nature, on some beetles, butterflies (their scales sporting these grooves) or birds. The main difference is that using the second method ensures “sharp” filtering, i. e. vivid colors, while natural pigments (first method) tend to have rather broad absorption and will often look muddy/brownish.

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