Reflectometer stage
===================

.. _reflectometer-stage-motor-direction:
.. figure:: FFT-reflectometer.png

  Drawing of the reflectometer stage with the hutch reference axes

The reflectometer diode can be moved on the reflected optical beam with the
reflectometer stage shown in `reflectometer-stage-motor-direction`_. The
positive motor direction is given in the table below.

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

Motor table:

===========  ===============
Stage Motor  Positive motion
===========  ===============
5            :green:`-Y`
6            :red:`-X`
===========  ===============

Laser in-coupling and sample blades
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To get the optical laser reflected on the reflectometer diode, it is necessary
to have an angled blade on the sample card. Depending on the sample position
(SAM_Z) the blade angle will be different as shown in
`LIN_in-coupling_blade`_ for LIN in-coupling and in `THz_in-coupling_blade`_
for THz stage in-coupling, as calculated in `elog1550`_.

.. _LIN_in-coupling_blade:
.. figure:: LIN_in-coupling_blade.png

  Blade angles for LIN in-coupling geometry as function of sample Z

.. _THz_in-coupling_blade:
.. figure:: THz_in-coupling_blade.png

    Blade angles for THz stage in-coupling geometry as function of sample Z

.. _elog1550: https://in.xfel.eu/elog/SCS+Instrument/1550