This document shows you how to use the program MieCalc, if
it is launched from a HTML-document (i.e., from a web page). Note
that some features of MieCalc such as storing output data in
ASCII-format, printing the plots etc. are only available in the stand
alone version of MieCalc
See also:
Basics
MieCalc is a very flexible program to calculate the optical and electromagnetic
scattering from a single homogeneous spherical particle illuminated by
a plane incident light wave (Mie theory). With MieCalc, you can study the
functional dependence of light-scattering observables as functions
of certain other parameters, for example:
-
extinction cross-section cext as a function of the particle diameter
d
-
scattered irradiance S11 as a function of the scattering angle theta
-
degree of linear polarization P at a given scattering angle as a function
of the particle radius r
-
albedo A and asymmetry factor g as functions of the imaginary
part of the refractive index of the particle
-
scattering efficiency qsca as a function of the wavelength and the complex
refractive index of the particle
-
backscattering cross-section Cb as a function of the frequency of the incident
radiation and the complex dielectric function of the particle.
-
and almost any other combination of parameters
Input Parameters
All quantities required as input for calculations are called "input parameters".
MieCalc supports a large set of input parameters:
-
the frequency, wavelength, inverse wavelength or wavenumber of the incident
radiation
-
the radius anddiameter of the particle
-
the relative dielectric function (permittivity) or the refractive index
of the surrounding medium
-
the complex relative dielectric function (permittivity) or the complex
refractive index of the particle
-
the scattering angle theta
Click here for a complete list of
parameters. Clearly, the set of input parameters is redundant: you can
use the radius r or the diameter d of the particle, or you
may enter the frequency f, the wavelength lambda or the wavenumber k to
specify the properties of the incident light. With this redundance
you can easily adjust MieCalc to your preferences.
There are three categories of input parameters:
-
Constants. These input parameters are kept at a fixed value during the
calculation.
-
Variables. A variable is specified by its range of variation and
the number of data points to be evaluated. There must be at most one variable
in a calculation. For instance, you can use the wavelength lambda,
the diameter d of the particle, the scattering angle theta, the refractive
index of the surrounding medium refmed, etc. as the variable. Any input
parameter can be used as a variable.
-
Tabulated parameters. These parameters are read in from the text area of
the program in ASCII format. There may be more than one tabulated
parameter in a calculation, but you cannot use variables and tabulated
parameters in the same calculation.
Output parameters
All quantities that can be plotted are called "output parameters". There
are many output parameters supported by MieCalc:
-
most input parameters can also be used as output parameters (typically,
the abscissa of a plot is such a parameter).
-
cross-sections for extinction, scattering, absorption, backscattering
-
efficiencies for extinction, scattering, absorption, backscattering
-
other integral scattering parameters such as albedo, asymmetry factor
-
angular scattering observables: scattered intensity for various states
of polarization, degree of linear polarization
Click here for a complete list of
parameters. In the calculations at least two output parameters must
be specified, one of them playing the role of the abscissa, the others
being plotted along the ordinate. For instance, you may specify the wavelength
as the abscissa and the extinction, scattering, and absorption efficiencies
Qext, Qsca, and Qabs for the ordinate.
Consistent and Complete Set of Parameters
In order to perform a calculation you must specify the output parameters
you are interested in and all input parameters which are
needed for the calculation. The program will check two things:
-
Consistency of input parameters. Input parameters must be uniquely defined,
there may be no ambiguities. For example, you must not specify the
radius r and the diameter d as input parameters, because the radius
can be calculated from the diameter. Other "forbidden" combinations are
-
frequency f and wavelength lambda, because one can calculate the free-space
wavelength of light from its frequency
-
dielectric function epsmed and refractive index refmed of surrounding medium,
because the latter is the square root of the former.
-
Completeness of input parameters. You must specify all input parameters
needed to calculate the output parameters.
If the input parameters are inconsistent or not complete,
the program issues a warning message and waits until acceptable input is
entered. Only if the input is OK are you able to run the program.
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