by Scott Prahl
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>
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
When comparing different Mie scattering codes, make sure that you're aware of the conventions used by each code. miepython makes the following assumptions:
- 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.
- 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.
Use pip:
pip install miepython
or conda:
conda install -c conda-forge miepython
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.
miepython is licensed under the terms of the MIT license.