miepython

by Scott Prahl

pypi github conda doi

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miepython is a pure Python module to calculate light scattering for non-absorbing, partially-absorbing, or perfectly-conducting spheres.

This code provides functions for calculating the extinction efficiency, scattering efficiency, backscattering, and scattering asymmetry. Moreover, a set of angles can be given to calculate the scattering for a sphere at each of those angles.

Mie computations are done following the procedure described by Wiscombe. This code has been validated against his results.

Full documentation at <https://miepython.readthedocs.io>

Version 3 changes

This version contains major changes to the code base and has API breaking changes. If you don’t need the new functionality for fields, then you can continue to use the last version with the old API: 2.5.5

Version 3.0 has many changes, but the major ones are:

  • a complete overhaul of API

  • added support to calculate Mie coefficients for fields inside sphere

  • future work will implement calculating electric and magnetic fields

Pay Attention!

When comparing different Mie scattering codes, make sure that you’re aware of the conventions used by each code. miepython makes the following assumptions:

  1. The imaginary part of the complex index of refraction for absorbing spheres is negative. Currently if you pass refractive indicies with a positive imaginary value, the refractive index is silently converted to a negative value before calculation.

  2. The scattering phase function is normalized so it equals the single scattering albedo when integrated over 4π steradians. The default normalization can now be changed.

Installation

Use pip:

pip install miepython

or conda:

conda install -c conda-forge miepython

An example

The following code:

import miepython as mie

m = 1.5 - 1j      # refractive index of sphere
d = 100           # nm diameter of sphere
lambda0 = 314.15  # nm wavelength in vacuum

qext, qsca, qback, g = mie.efficiencies(m, d, lambda0)

print("The extinction efficiency  is %.3f" % qext)
print("The scattering efficiency  is %.3f" % qsca)
print("The backscatter efficiency is %.3f" % qback)
print("The scattering anisotropy  is %.3f" % g)

should produce:

The extinction efficiency  is 2.336
The scattering efficiency  is 0.663
The backscatter efficiency is 0.573
The scattering anisotropy  is 0.192

There are a few short python scripts in the github repository.

Absorbing and non-absorbing spheres Glass spheres with resonance spike Water Droplets Gold nanospheres

License

miepython is licensed under the terms of the MIT license.