This description is a copy of in . The following definitions are used:
The fraction of scattered light for small/large angle scatter is
with a correction factor of the LSF probability density for
large angle scattering of
where & are stored in CCF LineSpreadFunc, and
is defined by
The power spectral densities are defined with respect to , with
and finally the density functions for small and large angle scatter
The intensity of the LSF for one bin in that has a range from
to is then given by
where the total fraction of non-scattered light is given by . The function that is implemented in the CAL does not include the last term (the -function), as is only the unscattered light and its contribution is taken care of by the calling task (rgsrmfgen).
In order to obtain the LSF, this needs to be convolved with the PSF of the mirror, which acts as a perturbation of . This is not performed by this function.