Guard stage
===========

.. _guard-stage-motor-direction:
.. figure:: FFT-guard.png

  Drawing of the guard stage looking upstream with the 4 different B4C blades.
  From `CAD File`_.

The guard stage is used to cut off stray light coming down the beamline and
is shown with its cover removed in :numref:`guard-stage-motor-direction`. The
motor positive direction of each of the four independent B4C blades is given
in the table below:

.. role:: red
.. role:: green
.. role:: blue
.. role:: gold

Motor table:

===========  =======================  ===============
Stage Motor  Blade (view downstream)  Positive motion
===========  =======================  ===============
1            :gold:`bottom`           :green:`+Y`
2            :red:`right`             :red:`+X`
3            :green:`top`             :green:`+Y`
4            :blue:`left`             :red:`+X`
===========  =======================  ===============

.. _CAD file: https://docs.xfel.eu/share/page/site/xfelwp86/document-details?nodeRef=workspace://SpacesStore/5c6735c3-c260-4e17-b095-c3dec5d24e5e