.. kiessig_calculator_help.rst

.. This is a port of the original SasView html help file to ReSTructured text
.. by S King, ISIS, during SasView CodeCamp-III in Feb 2015.

Kiessig Thickness Calculator Tool
=================================

Description
-----------

This tool estimates real space dimensions from the position or spacing of
features in reciprocal space.  In particular a particle of size $d$ will
give rise to Bragg peaks with spacing $\Delta q$ according to the relation

.. math::

    d = 2\pi / \Delta q

Similarly, the spacing between the peaks in Kiessig fringes in reflectometry
data arise from layers of thickness $d$.

.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

Using the tool
--------------

To get a rough thickness or particle size, simply type the fringe or peak
position (in units of 1/|Ang|\) and click on the *Compute* button.

.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

.. note::  This help document was last changed by Romain Conan, 12Nov2025