All Questions
15
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Complex Refractive Indices, Absorption, and Transparency
A complex refractive index is defined as $n = n_0 + \kappa$ where $n_0$ is the "standard" refractive index, and $\kappa$ is the optical extinction coefficient. The optical extinction ...
- 203
1
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1
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147
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Refractive index of titanium dioxide films as a function of wavelength for 400 C ° annealed films
I used UV-Vis/NIR spectrophotometer to extract the measurements of refractive index %R corresponding with wavelengths in the range of 190-1100 nm of TiO2 thin film deposited on FTO glass substrate. ...
- 11
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26
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Water vapor: refractive index and extinction coefficient ($n$ and $k$)
Looking for optical properties of water vapor (index of refraction and extinction coefficient) as a function of wavelength.
- 1
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164
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How to find the fraction of light absorbed by a surface?
How to find the fraction of light absorbed by a surface? What values do we need?
I am trying to find the fraction of light absorbed by a surface when it's dry and when it's wet.
I have something ...
- 13
1
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1
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73
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Imaginary part of semiconductors index of refraction
I understand that the index of refraction is complex and can be expressed as such: $ \widetilde{\eta} = \eta + i \kappa $. However I’ve been searching for a bit and I am unable to find the derivation ...
- 109
1
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1
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255
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Why exactly does a material reflect/absorb/refract light? [duplicate]
What is the property of the molecules of the material that causes it to behave differently when it interacts with light. Is it the frequency of the material?
I was thinking that the resonant ...
- 581
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1
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375
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Why does the Complex Index of Refraction take part in the Reflection?
I'm aware that in Optics, the complex index-of-refraction $\eta = n+ik$ is used, which famously leads to the reflection property at an incident angle, i.e. Fresnel's law:
$$R=\frac{(n-1)^2+k^2}{(n+1)^...
10
votes
2
answers
872
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Paint: "Darker When Dry"?
A great question I enjoy bringing up is why are things, in general, "darker when wet". This applies to porous and granular materials like wetted stone, paper, sand etc. It also comes up in ...
- 109
2
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1
answer
1k
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Complex refractive index and absorption
I have a quite plain and simple question: Why is the imaginary part of the refractive index negative? I read it is to allow a positive sign in case of absorption. But how/why? I don't see why it ...
- 1,507
6
votes
1
answer
646
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Complex part of second-order susceptibility in nonlinear optics
In optics, the absorption of photons by a material can be described by considering the material's susceptibility. For linear absorption (involving a single photon), we think about the imaginary part ...
- 372
1
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141
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Dielectric constants from refractive index and absorption spectra
I would like to calculate the dispersion relation (dielectric constants $\varepsilon'$ and $\varepsilon''$) from two spectra: refractive index $n$ and absorption (in %). I tried to use the relation $$\...
- 4,788
6
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1
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332
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Is there a zone where 'colour' overlaps between double rainbows?
Someone on social media posted this question based on a conversation with their (very cluey and creative) kid.
Is there a zone between double rainbows where the 'colour' overlaps?
This would be in ...
- 1,116
2
votes
1
answer
66
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Absorption Magnification
I'm working on an optical project about the absorption of glass sheet and I need to measure the intensity of laser beam that has passed the glass sheet and compare that with the intensity of laser ...
- 765
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0
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809
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How to calculate the Refractive index of a glass sheet
My question is how to find the $n$ of a glass sheet with just aiming a laser beam to that.
I've got lot of ways that let me find the $n$ ( Refractive index ) but I need the whole part of the ...
- 765
3
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2
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1k
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Light-matter interaction and an object's appearance
I am taking a course in Computer Graphics, and the teacher said we could put materials in there main categories:
mirror like
glossy or specular
diffuse
He suggested that the law of reflection is ...
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