What is Mie theory in particle size distribution?
Mie theory uses the refractive index difference between the particle and the dispersing medium to predict the intensity of the scattered light. It also describes how the absorption characteristics of the particle affect the amount of light which is transmitted through the particle and either absorbed or refracted.
What causes Mie scattering?
Mie scattering occurs when the diameters of atmospheric particulates are similar to or larger than the wavelengths of the scattered light. Dust, pollen, smoke and microscopic water droplets that form clouds are common causes of Mie scattering.
What is the difference between Mie and Rayleigh scattering?
Rayleigh line refers to the unshifted central peak observed in the spectroscopic analysis of scattered light. Mie scattering refers primarily to the elastic scattering of light from atomic and molecular particles whose diameter is larger than about the wavelength of the incident light.
What does Mie scattering look like?
In Mie scattering, the particles are always larger and instead of light being scattered in all directions, more light is scattered backwards rather than forwards. When observed, the scattering effect looks rather like an antenna protruding in one direction.
Is Mie scattering polarized?
Mie theory calculates the angular dependence of the two elements, S1(θ) and S2(θ), of the Scattering matrix, from which the scattered intensities of polarized light are computed (see example). The scattering pattern is also used to calculate the anisotropy, g, of scattering by the particle.
What is a Mie resonance?
The Mie resonances of dielectric inclusions provide a novel mechanism for the creation of magnetic or electric resonance based on displacement currents, and offer a simpler and more versatile route for the fabrication of isotropic metamaterials operating at higher frequencies.
What the similarities Rayleigh scattering and Mie scattering?
In the Rayleigh or linear scattering, the size of the scattering particles is smaller than the radiation wavelength and in the Mie-scattering the size of the scattering particles and the wavelength of radiation is the same.
Is Mie scattering elastic?
Mie scattering is elastic scattered light of particles that have a diameter similar to or larger than the wavelength of the incident light. The Mie signal is proportional to the square of the particle diameter.
What is linear and non linear scattering?
In linear scattering, attenuation occurs when optical power is transferred from one mode to another keeping frequency unaltered. Non linear scattering occurs when frequency is changed during optical power transfer.
What is linear scattering?
Linear scattering results in the transfer of some or all of the optical (light) power contained within one propagating mode to a different mode linearly. Thus leads to attenuation of power because some of the transferred power may escape to a radiation mode which will absorb the power without reflecting it back.
What is the difference between linear and nonlinear scattering?
In optics, linear scattering is “power-independent” whereas non-linear scattering is “power dependent” phenomena. This type of scattering processes are power dependent and occurs due to change in frequency during optical power transferring, which causes disproportionate attenuation at high optical power levels.
How does the size of particles affect the scattering of light?
The scattering of light and the color of the scattered light depends upon the size of the particles. Smaller particles scatter the light of shorter wavelength, like blue and violet and larger particles scatter longer wavelength like, red and orange.
What is fundamental difference between SBS and SRS?
The fundamental difference is that, the optical phonons participate in SRS while SBS is through acoustic phonons. As a result of this difference, SBS occurs only in one direction i.e., backward while SRS can occur in both directions- forward and backward.
Which are linear and nonlinear scattering losses?
Non linear scattering occurs when frequency is changed during optical power transfer. Linear scattering take place in forward direction and non-linear scattering take place in either forward or backward direction. Frequency shift is minimum in linear scattering.
Do smaller or larger particles scatter more light?
Large particles scatter more light than small ones. The decrease in scattered light intensity happens by about a factor of 106, meaning that a 100 nm particle has 10 times less diameter, 1000 times less volume, and a million times less static light scattering intensity compared to a 1000 nm particle.
Why do smaller particles scatter light of shorter wavelength?
Air molecules scatter light in this way because they are very small (much smaller than the wavelength of visible light). Violet has the shortest wavelength and is scattered the most. However there isn’t as much violet in sunlight as there is blue and green.
What is Mie scattering pattern?
Mie scattering, at some distance from the particle in the direction of the incident light, is a pattern that will develop depending on the size of the particle and the wavelength of the incident light. From this Mie scattering pattern information related to the size distribution of the material can be obtained.
What is the size limit of Mie scattering theory?
Mie scattering theory has no upper size limitation, and converges to the limit of geometric optics for large particles. Angular part of magnetic and electric vector spherical harmonics. Red and green arrows show the direction of the field.
When to use Fraunhofer diffraction theory vs Mie scattering?
Yet, when the particle size is smaller than ten times the laser wavelength, in particular, in measurement in the sub-micron region, the Fraunhofer diffraction theory can no longer be used since a wide-angle light intensity distribution pattern is required. In this case, the Mie scattering theory must always be used.
What is the relationship between particle size and light intensity distribution pattern?
With the laser diffraction/scattering method, particle size is specified from the light intensity distribution pattern. For this, the correspondence relationship between particle size and light intensity distribution pattern must be known in advance. The Fraunhofer diffraction theory and Mie scattering theory are used to obtain this relationship.