Talk:Mie scattering

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Applications

I've Removed mention to 'Bilge Alarm' and 'Oil Discharge Monitor'. These are irrelevant to the theory. Can you imagine if, for example, we made mention to all the devices which are based on Maxwell's equations? It would be an enormous list, bigger than the article itself. It's easy to see that such lists belong not in an article on the theory, but on a separate page listing the various devices based on the theory. Even then, it seems the mention should limit itself to device types, not brands. —Preceding unsigned comment added by 75.0.192.40 (talk) 13:26, 29 June 2008 (UTC)

Question about usage of the term "Mie solution"

Would someone familiar with this theory know why the term "Mie solution" (with no article) is used as the singular? Coming from an unrelated field, sentences such as "Mie theory is not a correct name because it is not a theory per se, rather Mie solution to Maxwell's equations should be used" sound like sentence fragments. To me, either "a/the Mie solution" or "Mie's solution" sound more grammatically correct (i.e., the name is used as an adjective and hence takes an article or just as a possessive). The former gibes with the plural that is used later on: "Mie solutions." —The preceding unsigned comment was added by 130.15.126.81 (talk) 14:43, 14 December 2006 (UTC).

in the book Scattering, Absorption, and Emission of Light by Small Particles by Mishchenko et al, the term Lorenz-Mie theory is used with no acknowledgment of its correctness, however, I believe it to be a proper usage. Csocean 13:12, 5 June 2007 (UTC)

Why isn't this article titled Mie Scattering? 124.168.195.76 (talk) 01:38, 4 September 2008 (UTC)

I agree - I've never heard of "Mie Theory" but I have come across "Mie Scattering" several times. --Noosentaal^·talk· 12:07, 22 May 2009 (UTC)

Mie theory and Mie scattering both seem common enough terms. Strangely Google gives more hits for "Mie scattering theory" than just "Mie scattering" which makes me a bit skeptical about its numbers. --catslash (talk) 18:27, 14 April 2010 (UTC)

Contradiction?

The lead seems to use the term Mie scattering to mean a scattering formula valid at all frequencies, but the new section (Comparison with Rayleigh scattering) uses the term for scatting exclusively in the geometric optics regime (or possibly resonant and GO regimes). Is one right? or both? --catslash (talk) 18:10, 14 April 2010 (UTC)

With the revised introduction the answer to this question should be clearer. The Mie calculation is always right but it really a pain for very large and very small particles.--DrPD (talk) 12:03, 11 July 2010 (UTC)

Rayleigh approximation (scattering)

Rayleigh Theory applies to the case where the particles are non-absorbing and much smaller than a wavelength. In this article, instead of finding anything related to Mie Theory, Rayleigh Theory (a special case for very tiny diploles, e.g. molecules), van de Hulst (a very special case of aerosol scattering where the particle size is large compared to the wavelength and optically soft, i.e. the index is close to 1) and Rayleigh-Glan theory (again, a very special case of where the particles are both small and the index is close to 1.)

Mie theory actually is a "theory" because it it attempts to model scatter based on certain assumptions which are known not to be strictly true, but close enough to be useful. The actual phenomenon is atmospheric scatter, and Mie theory is an attempt to develop a mathematical theory to predict the scatter associated with particles of arbitrary size and index.

It should be noted that physicists often talk of molecular scatter as "Rayleigh scatter" and aerosol or particulate scatter as "Mie scatter." This is not strictly correct and can be misleading.

At any rate, this article gives the impression that Rayleigh theory is an approximation to Mie scatter. That is quite misleading, especially since Rayleigh Theory is widely used for molecular scatter while Mie Theory is generally only used for aerosol scatter.

Here is some good reading material to become familiar with. Obviously the Mie Theory is very tough going, requiring an understanding of Maxwell's equations to understand the theory. Maybe for this overview article, one should stick with the overview approach of David W. Hahn.

David W. Hahn (July, 2009). "Light Scattering Theory" (PDF). Retrieved 2013-12-17. {{cite web}}: Check date values in: |date= (help)‎

The above Hahn article is a good top level overview of both Rayleigh Theory (treating particles less than a wavelength of light in diameter) and "Mie Theory" (treating particles larger than a wavelength of light.)

"Mie Theory" (PDF). Retrieved 2013-12-17.‎

The above thesis dives deeply into Mie Theory and develops the equations starting from Maxwell's equations. As you can see, there a very strong angular dependence in Mie theory, called the "phase function" which is not mentioned in this wiki article.

This entire wiki section "Approximations" needs a major re-write.

The introduction section correctly mentions the relationship to Rayleigh scatter, but the "Approximations" section completely contradicts the introduction.

1. Rayleigh Theory is not an approximation to Mie Theory and is only a special case that should simply refer to the Rayleigh scatter entry in wiki.

2. Rayleigh-Gans and van de Hulst only apply to optically soft particles, in other words, where the particles have no appreciable Fresnel reflection. This should be considered a special case of Mie Theory and not an approximation to it, in the same way that Newtonian dynamics are not an approximation to relativity, but merely a special case when velocities and energies are very low.

Rocket Laser Man (talk) 23:26, 16 December 2013 (UTC)

Yes, not explaining or even describing the Mie theory is a major deficiency of the article. Reference 3, has links to two translations of Mie's original paper which are fairly readable (there is a slight complication: for no apparent reason he starts with a spherical coordinate system such that the incident radiation is on the equator, and then has to transform to another for which the incident radiation is on the pole).

Mie's solution is an exact solution of Maxwell's equations for a plane wave incident on a homogeneous sphere of any size, any permittivity and any conductivity, so I don't understand your reference to certain assumptions which are known not to be strictly true.

In the low-frequency limit, Mie's solution (which exactly satisfies Maxwell's equations) is asymptotic to Rayleigh's solution (as far as I understand the latter), so how is Rayleigh's result not an approximation to Mie Theory? --catslash (talk) 01:39, 8 January 2014 (UTC)

Results of the Mie solution

I think the article would be much more complete if a good-will people added a general description/discussion of the results of the application of Mie to typical problems, as e.g. a conductive sphere (as in the graph already reported), or a dielectric sphere, or an assembly of spheres having a suitable distribution of diameters/properties (fog, smoke, milk). --GianniG46 (talk) 13:24, 31 May 2010 (UTC)

Mie Scatting Approximation

The article currently says

"The Mie scattering formalism can be approximated[16] by the equation

Q = 2 – (4/p)sin p + (4/p2)(1 – cos p)

Where Q is the scattering cross-section, p = 4πa(n – 1)/λ, a is the radius of the sphere, n the ratio of refractive indices inside and outside of the sphere, and λ the wavelength of the light"

Q is unitless as presented, so does not represent a cross section. I suppose the Wahlstra paper cited must have this detail. I think it is rather important for the article to explain how to use "Q" as a number with units. OriEri (talk) 17:05, 16 August 2010 (UTC)

Clarified in the article. Materialscientist (talk) 00:08, 17 August 2010 (UTC)

Why is the geometrical cross section mentioned as 4πa², not πa² ? For light it should be just the area of the particle seen from one side (not the doubled diameter (2a)² like we would have in a billiard problem). This might be an error... 134.76.234.36 (talk) 13:06, 6 September 2010 (UTC)

This is surely a typo - I shall change it. --catslash (talk) 14:45, 6 September 2010 (UTC)

It's not a typo. The scattering cross section is twice the geometrical cross section. I'm in a hurry, but shouldn't this be titled "The Fraunhofer approximation"? Would be nice to include the schematic from van de Hulst showing where the different approximations (Rayleigh, Fraunhofer, anomolous diffraction) apply in a graph of optical constrast versus dimensionless size. AlanParkerFrance (talk) 07:38, 10 October 2012 (UTC)

But the geometric cross section is πa² - and twice this would be 2πa² not 4πa². The article says that the scattering cross section is Q times the geometric cross section, and according to the formula Q does tend to 2 for λ >> a in agreement with your assertion. --catslash (talk) 00:43, 8 January 2014 (UTC)

Gas particles

The article mentions gas particles twice (at least), when it describes scattering by particles << wavelength. But atmospheric gas is made of atoms or molecules. On the other hand, aerosol particles and clusters are not gaseous. Wouldn't it be better to call them either 'particles' or 'gas molecules'? Northfox (talk) 05:44, 16 January 2011 (UTC)

Move to "Mie scattering"?

Seeing as the article talks about "Mie theory" being a misnomer, would anyone object to moving the article title to "Mie scattering"? That seems to be the favoured title in textbooks. Papa November (talk) 10:43, 7 August 2011 (UTC)

I'd like to know which books. I've always (=35 years) used "Mie theory", even if Lorentz-Mie is more historically accurate. The term Mie scattering is unfamiliar to me. The terminology that we use may well be domain specific, so let's be careful. I'm a physical chemist and expert in light scattering for particle characterization. Since Mie theory always applies, the term "Mie scattering" seems unhelpful. How about "Mie theory of light scattering". Well, it applies to all electromagnetic radiation so that is arguably not great either. so add "and other electromagnetic radiation", like Kerker's book title. I just found a nice review article by Mischenko (NASA), probably the world's leading theorist in this area (Bulletin of the American Meterological Society, 2008). He explains all this very well. Will link to it when I have time. AlanParkerFrance (talk) 07:31, 10 October 2012 (UTC)

Date?

The article is missing vital information: When and in what publication did Mie propose his theory? It should also be noted that Johann Wolfgang von Goethe was first to study and theorize on its effects as well as those of Rayleigh scattering in his Theory of Colours in 1810. Goethe's conclusions were basically that Rayleigh scattering (resulting in a violet-cyan spectrum) was due to light interacting with black objects (such as the blackness of space), that Mie scattering (resulting in a yellow-magenta spectrum) was due to light interacting with turbid objects (such as earth's atmosphere), and the larger the angle of the sunlight reaching us (such as during sunrise and sundown), the more it is shifted towards the Y-M spectrum because of having to cross a much larger mass of turbid atmosphere than when reaching us from above, where it has to cross a much smaller amount of turbid atmosphere. --2.240.198.214 (talk) 20:42, 16 March 2014 (UTC)