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Relationship between the refractive index and absorption

by asdfghhjkl
Tags: absorption, index, refractive, relationship
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asdfghhjkl
#1
Nov14-13, 06:12 AM
P: 5
Hello,

I was wondering is there a relation between the refractive index of the material and the amount of light the material absorbs (e.g. the higher n means higher absorption)? If so what is then a relation between the intensity of the light and the refractive index?

p.s. I am trying to apply this to some geological thin section observations, thus a simple explanation would be appreciated.

Thank you :)
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adjacent
#2
Nov14-13, 06:34 AM
PF Gold
adjacent's Avatar
P: 1,466
Quote Quote by asdfghhjkl View Post
Hello,

I was wondering is there a relation between the refractive index of the material and the amount of light the material absorbs (e.g. the higher n means higher absorption)? If so what is then a relation between the intensity of the light and the refractive index?

p.s. I am trying to apply this to some geological thin section observations, thus a simple explanation would be appreciated.

Thank you :)
There is no relation between the intensity of light and the refractive index.Refractive index depends on the speed of light through the medium.It varies with wavelength too.
asdfghhjkl
#3
Nov14-13, 06:38 AM
P: 5
Ok, thank you.

adjacent
#4
Nov14-13, 06:49 AM
PF Gold
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P: 1,466
Relationship between the refractive index and absorption

Quote Quote by asdfghhjkl View Post
Ok, thank you.
Please give thanks by using the "thanks" button.
DrDu
#5
Nov14-13, 07:01 AM
Sci Advisor
P: 3,564
There is a relation between absorption and refractive index which is known as Kramers Kronig relation:
http://www.rp-photonics.com/kramers_...relations.html
However, to deduce the one from the other, you need to know the absorption or refractive index ideally for all frequencies.
Andy Resnick
#6
Nov14-13, 08:23 AM
Sci Advisor
P: 5,513
Quote Quote by asdfghhjkl View Post
Hello,

I was wondering is there a relation between the refractive index of the material and the amount of light the material absorbs (e.g. the higher n means higher absorption)? If so what is then a relation between the intensity of the light and the refractive index?
Echoing DrDu, absorption is often modeled by allowing the refractive index to be complex-valued (say n = η + iκ) the real part η is the 'refractive' component and the imaginary part κ the 'absorption' component. The components are not independent but related through the Kramers-Kronig relation.
Claude Bile
#7
Nov15-13, 07:44 AM
Sci Advisor
P: 1,474
The intensity-dependent component of the refractive index is known as the Kerr nonlinearity (real part) and saturable absorption (imaginary part).

Claude.


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