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Figure 7
Algorithm for generating an initial estimate of the undistorted scattering [IR(Qz)] from experimental GISAXS data [Id(qz)]. The experimental intensity is first divided into contributions from the transmitted and reflected channels (Tc and Rc) based on known transmission/reflectivity curves ([|Tc|^{2}] and [|Rc|^{2}]) and an arbitrary guess for the ratio between the channels (w). The two channels are both undistorted into reciprocal space, which provides two predictions for the true scattering (which should agree). The difference between these predictions is used to compute an improved estimate for IR. This IR estimate can be distorted to yield new estimates for the contributions from the two channels, which provides an improved estimate for w. This new w estimate can be fed back as an improved initial guess. (Thick faded lines show true scattering contributions, while χ shows the corresponding residuals; these are of course not known during reconstruction of experimental data.) By iterating through this procedure, the algorithm converges towards a self-consistent prediction for w(qz) and IR(Qz).

IUCrJ
Volume 5| Part 6| November 2018| Pages 737-752
ISSN: 2052-2525
https://doi.org/10.1107/S2052252518012058